Acoustic output device

ABSTRACT

The present disclosure relates to a pair of glasses. The pair of glasses may include a frame, one or more lenses, and one or more temples. The pair of glasses may further include at least one low-frequency acoustic driver, at least one high-frequency acoustic driver, and a controller. The at least one low-frequency acoustic driver may be configured to output sounds from at least two first guiding holes. The at least one high-frequency acoustic driver may be configured to output sounds from at least two second guiding holes. The controller may be configured to direct the low-frequency acoustic driver to output the sounds in a first frequency range and direct the high-frequency acoustic driver to output the sounds in a second frequency range. The second frequency range may include one or more frequencies higher than one or more frequencies in the first frequency range.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of International Patent ApplicationNo. PCT/CN2020/070542, filed on Jan. 6, 2020, which claims priority ofChinese Patent Application No. 201910364346.2, filed on Apr. 30, 2019,Chinese Patent Application No. 201910888762.2, filed on Sep. 19, 2019,and Chinese Patent Application No. 201910888067.6, filed on Sep. 19,2019, the entire contents of each of which are incorporated herein byreference.

TECHNICAL FIELD

The present disclosure relates to smart devices, in particular, to anacoustic output device.

BACKGROUND

With the development of acoustic output technology, acoustic outputdevices have been widely used. An open binaural acoustic output deviceis a portable audio output device that facilitates sound conductionwithin a specific range. Compared with conventional in-ear and over-earheadphones, the open binaural acoustic output device may have thecharacteristics of not blocking and not covering the ear canal, allowingusers to obtain sound information of an ambient environment while theuser is listening to music, improving safety and comfort of the user.Due to the use of an open structure, a sound leakage of the openbinaural acoustic output device may be more serious than that ofconventional headphones. In addition, with the development of voice andcommunication technologies, some acoustic output devices may also havesound receiving functions. However, conventional acoustic output devicesmay include one single microphone to receive sounds. During the processof receiving the sound, external noises may also be recorded by themicrophone, thereby affecting the performance of receiving the sound ofthe acoustic output device. Therefore, it is desirable to provide anacoustic output device, thereby increasing listening volume, reducingsound leakage of the acoustic output device, and improving the soundreceiving performance of the acoustic output device.

SUMMARY

According to an aspect of the present disclosure, a pair of glasses areprovided. The pair of glasses may include a frame, one or more lenses,and one or more temples. The pair of glasses may further include atleast one low-frequency acoustic driver, at least one high-frequencyacoustic driver, and a controller. The at least one low-frequencyacoustic driver may be configured to output sounds from at least twofirst guiding holes. The at least one high-frequency acoustic driver maybe configured to output sounds from at least two second guiding holes.The controller may be configured to direct the low-frequency acousticdriver to output the sounds in a first frequency range and direct thehigh-frequency acoustic driver to output the sounds in a secondfrequency range. The second frequency range may include one or morefrequencies higher than one or more frequencies in the first frequencyrange.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is further described in terms of exemplaryembodiments. These exemplary embodiments are described in detail withreference to the drawings. These embodiments are non-limiting exemplaryembodiments, in which like reference numerals represent similarstructures throughout the several views of the drawings, and wherein:

FIG. 1 is a schematic diagram illustrating an exemplary dual-point soundsource according to some embodiments of the present disclosure;

FIG. 2 is a schematic diagram illustrating variations of leakage soundsof a dual-point sound source and a single point sound source with afrequency according to some embodiments of the present disclosure;

FIG. 3A and FIG. 3B are graphs illustrating changes of a volume of thenear-field sound and a volume of the far-field leakage with a distanceof two point sound sources of a dual-point sound source according tosome embodiments of the present disclosure;

FIG. 4 is a schematic diagram illustrating an exemplary acoustic outputdevice according to some embodiments of the present disclosure;

FIG. 5 is a schematic diagram illustrating an exemplary acoustic outputdevice according to some embodiments of the present disclosure;

FIG. 6A and FIG. 6B are schematic diagrams illustrating exemplaryprocesses for sound output according to some embodiments of the presentdisclosure;

FIG. 7A and FIG. 7B are schematic diagrams illustrating exemplaryacoustic output devices according to some embodiments of the presentdisclosure;

FIGS. 8A-8C are schematic diagrams illustrating exemplary acousticroutes according to some embodiments of the present disclosure;

FIG. 9 is an exemplary graph illustrating sound leakage under a combinedaction of two sets of dual-point sound sources according to someembodiments of the present disclosure;

FIG. 10 is a schematic diagram illustrating an exemplary acoustic outputdevice according to some embodiments of the present disclosure;

FIG. 11 is a schematic diagram illustrating two point sound sources anda hearing position according to some embodiments of the presentdisclosure;

FIG. 12 is a graph illustrating a change of a volume of a hearing soundof a dual-point sound source with different distances along with afrequency according to some embodiments of the present disclosure;

FIG. 13 is a graph illustrating a change of a normalized parameter of adual-point sound source in a far-field along with a frequency accordingto some embodiments of the present disclosure;

FIG. 14 is a schematic diagram illustrating an exemplary baffle disposedbetween two point sound sources of a dual-point sound source accordingto some embodiments of the present disclosure;

FIG. 15 is a graph illustrating a change of a volume of a hearing soundalong with a frequency when an auricle is arranged between two pointsound sources of a dual-point sound source according to some embodimentsof the present disclosure;

FIG. 16 is a graph illustrating a change of a volume of a leakage soundalong with a frequency when an auricle is arranged between two pointsound sources of a dual-point sound source according to some embodimentsof the present disclosure;

FIG. 17 is a graph illustrating a change of a normalized parameter alongwith a frequency when two point sound sources of a dual-point soundsource of an acoustic output device are disposed on two sides of anauricle according to some embodiments of the present disclosure;

FIG. 18 is a graph illustrating a change of a volume of hearing soundand a volume of leakage sound along with a frequency with and without abaffle between two point sound sources of a dual-point sound sourceaccording to some embodiments of the present disclosure;

FIG. 19 is a graph illustrating changes of a volume of a hearing soundand a volume of a leakage sound along with a distance between two pointsound sources of a dual-point sound source at a frequency of 300 Hz andwith or without a baffle according to some embodiments of the presentdisclosure;

FIG. 20 is a graph illustrating changes of a volume of a hearing soundand a volume of a leakage sound along with a distance between two pointsound sources of a dual-point sound source at a frequency of 1000 Hz andwith or without a baffle according to some embodiments of the presentdisclosure;

FIG. 21 is a graph illustrating changes of a volume of a hearing soundand a volume of a leakage sound along with a distance between two pointsound sources of a dual-point sound source at a frequency of 5000 Hz andwith or without a baffle according to some embodiments of the presentdisclosure;

FIG. 22 is a graph illustrating a change of a volume of hearing soundalong with a frequency when a distance d between two point sound sourcesof a dual-point sound source is 1 cm according to some embodiments ofthe present disclosure;

FIG. 23 is a graph illustrating a change of a volume of a hearing soundalong with a frequency when a distance d between two point sound sourcesdual-point sound source is 2 cm according to some embodiments of thepresent disclosure;

FIG. 24 is a graph illustrating a change of a volume of a hearing soundalong with a frequency when a distance d of point sound sources of adual-point sound source is 4 cm according to some embodiments of thepresent disclosure;

FIG. 25 is a graph illustrating a change of a normalized parameter alongwith a frequency when a distance d between two point sound sources of adual-point sound source is 1 cm according to some embodiments of thepresent disclosure;

FIG. 26 is a graph illustrating a change of a normalized parameter alongwith a frequency when a distance d between two point sound sources of adual-point sound source is 2 cm according to some embodiments of thepresent disclosure;

FIG. 27 is a graph illustrating a change of a normalized parameter alongwith a frequency when a distance d between two point sound sources of adual-point sound source is 4 cm according to some embodiments of thepresent disclosure;

FIG. 28 is a schematic diagram illustrating hearing positions accordingto some embodiments of the present disclosure;

FIG. 29 is a graph illustrating a volume of hearing sound generated by adual-point sound source without baffle at different hearing positions ina near field along with a frequency according to some embodiments of thepresent disclosure;

FIG. 30 is a graph illustrating a change of a normalized parameter of ahearing sound at different hearing positions in a near field of adual-point sound source without baffle along with a frequency accordingto some embodiments of the present disclosure;

FIG. 31 is a graph illustrating a volume of a hearing sound at differenthearing positions in a near field of a dual-point sound source with abaffle along with a frequency according to some embodiments of thepresent disclosure;

FIG. 32 is a graph illustrating a normalized parameter at differenthearing positions of a dual-point sound source with a baffle along witha frequency according to some embodiments of the present disclosure;

FIG. 33 is a diagram illustrating a dual-point sound source and a baffleaccording to some embodiments of the present disclosure;

FIG. 34 is a graph illustrating a change of a volume of a sound in anear-field along with a frequency when a baffle is at differentpositions according to some embodiments of the present disclosure;

FIG. 35 is a graph illustrating a change of a volume of a leakage soundin a far-field along with a frequency when a baffle is at differentpositions according to some embodiments of the present disclosure;

FIG. 36 is a graph illustrating a change of a normalized parameter alongwith a frequency when a baffle is at different positions according tosome embodiments of the present disclosure;

FIG. 37 is a structural diagram illustrating another exemplary acousticoutput device according to some embodiments of the present disclosure;

FIG. 38 is a schematic diagram illustrating exemplary glasses accordingto some embodiments of the present disclosure;

FIG. 39 is a schematic diagram illustrating a cross-sectional view of atemple of exemplary glasses according to some embodiments of the presentdisclosure;

FIG. 40 is a schematic diagram illustrating guiding holes on a temple ofexemplary glasses according to some embodiments of the presentdisclosure;

FIG. 41 is a schematic diagram illustrating a cross-sectional view of atemple of exemplary glasses according to some embodiments of the presentdisclosure;

FIG. 42 is a schematic diagram illustrating guiding holes on a temple ofexemplary glasses according to some embodiments of the presentdisclosure;

FIG. 43 is a schematic diagram illustrating guiding holes on a temple ofexemplary glasses according to some embodiments of the presentdisclosure;

FIG. 44 is a schematic diagram illustrating a microphone noise reductionsystem according to some embodiments of the present disclosure;

FIG. 45A is a schematic diagram illustrating an exemplary microphonenoise reduction system according to some embodiments of the presentdisclosure;

FIG. 45B is a schematic diagram illustrating an exemplary microphonenoise reduction system according to some embodiments of the presentdisclosure;

FIG. 46A is a schematic diagram illustrating an exemplary frequencyresponse of a first microphone and an exemplary frequency response of asecond microphone according to some embodiments of the presentdisclosure;

FIG. 46B is a schematic diagram illustrating an exemplary frequencyresponse of a first microphone and an exemplary frequency response of asecond microphone according to some embodiments of the presentdisclosure;

FIG. 47 is a schematic diagram illustrating an exemplary sub-band noisesuppression sub-unit according to some embodiments of the presentdisclosure;

FIG. 48 is a schematic diagram illustrating a phase modulation signalaccording to some embodiments of the present disclosure;

FIG. 49A is a schematic diagram illustrating exemplary glasses accordingto some embodiments of the present disclosure;

FIG. 49B is a schematic diagram illustrating exemplary glasses accordingto some embodiments of the present disclosure;

FIG. 50A is a schematic diagram illustrating a temple of exemplaryglasses according to some embodiments of the present disclosure;

FIG. 50B is a schematic diagram illustrating a temple of exemplaryglasses according to some embodiments of the present disclosure;

FIG. 51A is a schematic diagram illustrating exemplary glasses accordingto some embodiments of the present disclosure;

FIG. 51B is a schematic diagram illustrating exemplary glasses accordingto some embodiments of the present disclosure;

FIG. 52A is a schematic diagram illustrating a temple of exemplaryglasses according to some embodiments of the present disclosure;

FIG. 52B is a schematic diagram illustrating exemplary glasses accordingto some embodiments of the present disclosure;

FIG. 53 is a schematic diagram illustrating exemplary glasses accordingto some embodiments of the present disclosure;

FIG. 54 is a schematic diagram illustrating exemplary glasses accordingto some embodiments of the present disclosure;

FIG. 55 is a schematic diagram illustrating components of an exemplaryacoustic output device according to some embodiments of the presentdisclosure;

FIG. 56 is a schematic diagram illustrating a connection of componentsof an acoustic output device according to some embodiments of thepresent disclosure;

FIG. 57 is a schematic diagram illustrating an exemplary power sourceaccording to some embodiments of the present disclosure;

FIG. 58 is a schematic diagram illustrating a voice control system of anexemplary acoustic output device according to some embodiments of thepresent disclosure;

FIG. 59 is a cross-sectional view of an exemplary open binaural earphoneaccording to some embodiments of the present disclosure;

FIG. 60 is a schematic diagram illustrating a sound generation structureof an exemplary open binaural earphone according to some embodiments ofthe present disclosure;

FIG. 61 is a cross-sectional view of a baffle of an exemplary openbinaural earphone according to some embodiments of the presentdisclosure;

FIG. 62 is a schematic diagram illustrating a position of a guiding holeaccording to some embodiments of the present disclosure;

FIG. 63A is a schematic diagram illustrating an exemplary frequencyresponse of a first loudspeaker unit and an exemplary frequency responseof a second loudspeaker unit according to some embodiments of thepresent disclosure;

FIG. 63B is a schematic diagram illustrating the exemplary frequencyresponse of the first loudspeaker unit and another exemplary frequencyresponse of the second loudspeaker unit according to some embodiments ofthe present disclosure; and

FIG. 64 is a schematic diagram illustrating an exemplary open binauralheadphone according to some embodiments of the present disclosure.

DETAILED DESCRIPTION

In order to illustrate the technical solutions related to theembodiments of the present disclosure, a brief introduction of thedrawings referred to in the description of the embodiments is providedbelow. Obviously, drawings described below are only some examples orembodiments of the present disclosure. Those skilled in the art, withoutfurther creative efforts, may apply the present disclosure to othersimilar scenarios according to these drawings. It should be understoodthat the purposes of these illustrated embodiments are only provided tothose skilled in the art to practice the application, and not intendedto limit the scope of the present disclosure. Unless apparent from thelocale or otherwise stated, like reference numerals represent similarstructures or operations throughout the several views of the drawings.

As used in the disclosure and the appended claims, without loss ofgenerality, the description of “speaker device”, “speaker”, or“headphone” will be used when describing the speaker relatedtechnologies in the present disclosure. This description is only a formof speaker application. For a person of ordinary skill in the art,“speaker device”, “speaker”, or “earphone” can also be replaced withother similar words, such as “player”, “hearing aid”, or the like. Infact, various implementations in the present disclosure may be easilyapplied to other non-speaker-type hearing devices. For example, forthose skilled in the art, after understanding the basic principles ofthe speaker device, multiple variations and modifications may be made informs and details of the specific methods and steps for implementing thespeaker device, in particular, an addition of ambient sound pickup andprocessing functions to the speaker device so as to enable the speakerdevice to function as a hearing aid, without departing from theprinciple. For example, a sound transmitter such as a microphone maypick up an ambient sound of the user/wearer, process the sound using acertain algorithm, and transmit the processed sound (or a generatedelectrical signal) to a user/wearer. That is, the speaker device may bemodified and have the function of picking up ambient sound. The ambientsound may be processed and transmitted to the user/wearer through thespeaker device, thereby implementing the function of a hearing aid. Forexample, the algorithm mentioned above may include a noise cancellationalgorithm, an automatic gain control algorithm, an acoustic feedbacksuppression algorithm, a wide dynamic range compression algorithm, anactive environment recognition algorithm, an active noise reductionalgorithm, a directional processing algorithm, a tinnitus processingalgorithm, a multi-channel wide dynamic range compression algorithm, anactive howling suppression algorithm, a volume control algorithm, or thelike, or any combination thereof.

The present disclosure provides an acoustic output device. When a userwears the acoustic output device, the acoustic output device may be atleast disposed on one side of the user's head, close to but not blockthe user's ear(s). The acoustic output device may be worn on the user'shead (e.g., an opening earphone designed as glasses, a headband, etc.),or on other parts of the user's body, such as an area of the user's neckor shoulder.

In some embodiments, the acoustic output device may include at least twosets of acoustic drivers. The at least two sets of acoustic drivers mayinclude at least one set of high-frequency acoustic drivers and at leastone set of low-frequency acoustic drivers. Each of the two sets ofacoustic drivers may be configured to generate sounds with certainfrequency ranges, and propagate the sounds outward through at least twoguiding holes acoustically coupled with the two sets of acousticdrivers, respectively. In some embodiments, the acoustic output devicemay include at least one set of acoustic drivers, and the soundgenerated by the at least one set of acoustic drivers may be propagatedoutward through at least two guiding holes acoustically coupled with theat least one set of acoustic drivers. In some embodiments, the acousticoutput device may include a baffle, and the at least two guiding holesmay be disposed on two side of the baffle, respectively. In someembodiments, the at least two guiding holes may be disposed on two sidesof the user's auricle when a user wears the acoustic output device. Inthis case, the auricle may be regarded as the baffle to separate the atleast two guiding holes, and the at least two guiding holes maycorrespond to different acoustic routes to the user's ear canal.

FIG. 1 is a schematic diagram illustrating an exemplary dual-point soundsource according to some embodiments of the present disclosure. Tofurther illustrate the effect of the setting of guiding holes of anacoustic output device on an output sound of the acoustic output device,and considering that the sound propagates outward from the guidingholes, the guiding holes of the acoustic output device may be regardedas sound sources for sound output in the present disclosure.

Merely for the convenience of description and illustration purposes,when a size of each of the guiding holes of the acoustic output deviceis relatively small, the each guiding hole may be regarded as a pointsound source. In some embodiments, any guiding holes disposed on theacoustic output device for outputting sound may be regarded as a singlepoint sound source of the acoustic output device. A sound pressure of asound field p generated by a single point sound source may berepresented by Equation (1) below:

$\begin{matrix}{{p = {\frac{j\omega\rho_{0}}{4\pi\tau}Q_{0}\exp{j\left( {{\omega t} - {kr}} \right)}}},} & (1)\end{matrix}$where co refers to an angular frequency, ρ_(o) refers to the airdensity, r refers to a distance between a target point and a soundsource, Q₀ refers to a volume velocity of the sound source, and k refersto a wave number. It can be seen that the sound pressure of the soundfield of the point sound source may be inversely proportional to thedistance between the target point to the point sound source. It shouldbe noted that a guiding hole for outputting a sound is regarded as apoint sound source in the present disclosure may be only an example ofthe principle and effect, which does not limit the shape and size of theguiding hole in practical applications. In some embodiments, a guidinghole with a relatively large area may be regarded as a surface soundsource and configured to propagate a sound outward. In some embodiments,the point sound source may also be realized by other structures, such asa vibrating surface, a sound radiating surface, or the like. For thoseskilled in the art, without paying any creative activity, it may beknown that the sound generated by the structures such as the guidinghole, the vibrating surface, and the sound radiating surface may beregarded as a point sound source at a spatial scale discussed in thepresent disclosure, which may have the same sound propagationcharacteristics and the same mathematical descriptions. Further, forthose skilled in the art, without paying any creative activity, it maybe known that the acoustic effect achieved in a case in which a soundgenerated by an acoustic driver may be propagated outward through atleast two guiding holes illustrated in the present disclosure may beachieved by other acoustic structures mentioned above, such as the soundgenerated by the at least one set of acoustic drivers may be propagatedoutward through at least one sound radiating surface. Other acousticstructures may be selected, adjusted, and/or combined according toactual needs, and the same acoustic output effect may be achieved. Theprinciple of propagating sound outward by a structure such as thesurface sound source may be similar to the principle of propagatingsound outward by the point sound source, which is not be repeatedherein.

As mentioned above, at least two guiding holes corresponding to the sameacoustic driver of an acoustic output device disclosed in the presentdisclosure may be used to construct a dual-point sound source, therebyreducing the sound radiated by the acoustic output device to thesurrounding environment. For convenience, the sound radiated by theacoustic output device to the surrounding environment may be referred toas a far-field leakage sound due to that the sound may be heard by otherpeople in the environment. The sound that the acoustic output deviceradiates to the ears of the user wearing the acoustic output device maybe referred to as a near-field sound due to the acoustic output deviceis close to the user. In some embodiments, the sound output by twoguiding holes (i.e., a dual-point sound source) may have a certain phasedifference. As used herein, a phase of the sound output by a point soundsource (e.g., a guiding hole) may also be referred to as a phase of thepoint sound source. When positions of the two point sound sources of thedual-point sound source and the phase difference satisfy certainconditions, the acoustic output device may show different sound effectsin the near-field (e.g., a hearing position of the user's ear) and thefar-field. For example, when the phases of the point sound sourcescorresponding to the two guiding holes are opposite, that is, when anabsolute value of the phase difference between the two point soundsources is 180 degrees, a far-field leakage may be reduced according tothe principle of sound wave anti-phase cancellation. More descriptionsregarding improving the sound output effect of an acoustic output devicemay be found in International Patent Application No. PCT/CN2019/130884filed on Dec. 31, 2019, the entire contents of which are herebyincorporated by reference.

As shown in FIG. 1, the sound pressure p of the sound field generated bythe dual-point sound source may be represented by Equation (2) below:

$\begin{matrix}{{p = {{\frac{A_{1}}{r_{1}}\exp{j\left( {{\omega t} - {kr_{1}} + \varphi_{1}} \right)}} + {\frac{A_{2}}{r_{2}}\exp{j\left( {{\omega t} - {kr_{2}} + \varphi_{2}} \right)}}}},} & (2)\end{matrix}$where A₁ and A₂ refer to the intensities of the two point sound sourcesof the dual-point sound source, respectively, φ₁ and φ₂ refer to thephases of the two point sound sources of the dual-point sound source,respectively, and r₁ and r₂ may be represented by Equation (3) below:

$\begin{matrix}\left\{ {\begin{matrix}{r_{1} = \sqrt{r^{2} + \left( \frac{d}{2} \right)^{2} - {2*r*\frac{d}{2}*\cos\theta}}} \\{r_{2} = \sqrt{r^{2} + \left( \frac{d}{2} \right)^{2} + {2*r*\frac{d}{2}*\cos\theta}}}\end{matrix},} \right. & (3)\end{matrix}$where r refers to a distance between any target point in space and acenter position of the two point sound sources of the dual-point soundsource, θ refers to an angle between a line connecting the target pointand the center position of the dual-point sound source and a line wherethe dual-point sound source locates (i.e., the line connecting the twopoint sound sources of the dual-point sound source), and d refers to adistance between the two point sound sources of the dual-point soundsource.

According to Equation (3), the sound pressure of the target point in thesound field may relate to the intensity of each point sound source, thedistance between the two point sound sources, the phases of the twopoint sound sources, and a distance between the target point and thedual-point sound source.

The dual-point sound source with different output performance may beformed by setting the sound guiding holes. In this case, a volume in thenear-field sound may be increased, and a volume of the leakage sound inthe far-field may be decreased. For example, an acoustic driver mayinclude a vibration diaphragm. When the vibration diaphragm vibrates,sounds may be transmitted from a front side and a rear side of thevibration diaphragm, respectively. The front side of the vibrationdiaphragm in the acoustic output device may include a front chamber fortransmitting a sound. The front chamber may be acoustically coupled witha sound guiding hole. The sound transmitted from the front side of thevibration diaphragm may be transmitted to the sound guiding hole throughthe front chamber and further transmitted outwards. The rear side of thevibration diaphragm in the acoustic output device may be provided with arear chamber for transmitting a sound. The rear chamber may beacoustically coupled with another sound guiding hole, and the soundtransmitted from the rear side of the vibration diaphragm may betransmitted to the sound guiding hole through the rear chamber andpropagate outwards. It should be noted that, when the vibrationdiaphragm vibrates, the front side and the rear side of the vibrationdiaphragm may generate sounds with opposite phases, respectively. Insome embodiments, the structures of the front chamber and rear chambermay be specially set so that the sounds output by the acoustic driver atdifferent sound guiding holes may meet specific conditions. For example,lengths of the front chamber and the rear chamber may be speciallydesigned such that sounds with a specific phase relationship (e.g.,opposite phases) may be output from the two sound guiding holes. As aresult, problems that the acoustic output device has a low volume in thenear-field and the sound leakage in the far-field may be effectivelyresolved.

Under certain conditions, compared to a single point sound source, thevolume of the far-field sound of the dual-point sound source may beincreased with the frequency. In other words, the leakage reductioncapability of the dual-point sound source in the far-field may bedecreased as the frequency increases. For further description, a curveof far-field leakage with frequency may be described in connection withFIG. 2.

FIG. 2 is a schematic diagram illustrating changes of leakage sounds ofa dual-point sound source and a single point sound source along with afrequency according to some embodiments of the present disclosure. Adistance between the two point sound sources of the dual-point soundsource in FIG. 2 may be constant, and the dual-point sound source mayhave the same (or substantially same) amplitude and opposite phases. Adotted line represents the variation of a volume of the leakage sound ofthe single point sound source at different frequencies. A solid linerepresents the variation of a volume of the leakage sound of thedual-point sound source at different frequencies. The abscissarepresents the sound frequency (f), and the unit is Hertz (Hz). Theordinate adopts a normalization parameter α to evaluate a volume of aleakage sound. The parameter α may be represented by Equation (4) below:

$\begin{matrix}{{\alpha = \frac{{❘P_{far}❘}^{2}}{{❘P_{ear}❘}^{2}}},} & (4)\end{matrix}$where P_(far) represents a sound pressure of the acoustic output devicein a far-field (i.e., the sound pressure of the far-field soundleakage). P_(ear) represents a sound pressure around the user's ear(s)(i.e., a sound pressure of the near-field sound). The greater the valueof α, the greater the far-field leakage sound relative to the near-fieldsound may be, which may indicate that the capability of the acousticoutput device for reducing the far-field sound leakage may be worse.

As shown in FIG. 2, when the frequency is below 6000 Hz, the far-fieldleakage sound produced by the dual-point sound source may be less thanthe far-field leakage sound produced by the single point sound source,and the far-field leakage sound may be increased as the frequencyincreases. When the frequency is close to 10000 Hz (e.g., about 8000 Hzor above), the far-field leakage sound produced by the dual-point soundsource may be greater than the far-field leakage sound produced by thesingle point sound source. In some embodiments, a frequencycorresponding to an intersection of the variation curves of thedual-point sound source and the single point sound source may bedetermined as an upper limit frequency that the dual-point sound sourcecan reduce the sound leakage.

For the purposes of illustration, when the frequency is relatively small(e.g., in a range of 100 Hz to 1000 Hz), the capability of reducingsound leakage of the dual-point sound source may be relatively strong(i.e., the value of a may be small which is below −80 decibel (dB)). Insuch a frequency band, increment of the volume of the hearing sound maybe determined as an optimization goal. When the frequency is relativelygreat, (e.g., in a range of 1000 Hz to 8000 Hz), the capability ofreducing sound leakage of the dual-point sound source may be relativelyweak (i.e., the value of a may be large which is above −80 dB). In sucha frequency band, decrease of the sound leakage may be determined as theoptimization goal.

Referring to FIG. 2, a frequency division point of the frequency may bedetermined based on the variation tendency of the capability of thedual-point sound source in reducing the sound leakage. Parameters of thedual-point sound source may be adjusted according to the frequencydivision point so as to reduce the sound leakage of the acoustic outputdevice. For example, the frequency corresponding to a with a specificvalue (e.g., −60 dB, −70 dB, −80 dB, −90 dB, etc.) may be used as thefrequency division point. Parameters of the dual-point sound source maybe determined by setting the frequency band below the frequency divisionpoint to improve volume of the near-field sound, and setting thefrequency band above the frequency division point to reduce thefar-field sound leakage. In some embodiments, a high-frequency band withrelatively high sound frequencies (e.g., a sound output by ahigh-frequency acoustic driver) and a low-frequency band with relativelylow sound frequencies (e.g., a sound output by a low-frequency acousticdriver) may be determined based on the frequency division point. Moredescriptions regarding the frequency division point may be foundelsewhere in the present disclosure (e.g., FIG. 4 and the relevantdescriptions thereof.)

In some embodiments, the measurement and calculation of the soundleakage may be adjusted according to the actual conditions. For example,an average value of amplitudes of the sound pressures of a plurality ofpoints on a spherical surface centered at the dual-point sound sourcewith a radius of 40 cm may be determined as the value of the soundleakage. A distance between the near-field hearing position and thepoint sound source may be less than a distance between the point soundsource and the spherical surface for measuring the far-field soundleakage. Optionally, the ratio of the distance between the near-fieldhearing position and the center of the dual-point sound source to theradius r may be less than 0.3, 0.2, 0.15, or 0.1. As another example,one or more points of the far-field position may be taken as theposition for measuring the sound leakage, and the sound volume of theposition may be taken as the value of the sound leakage. As anotherexample, a center of the dual-point sound source may be used as a centerof a circle, and sound pressure amplitudes of two or more points evenlysampled according to a certain spatial angle in the far-field may beaveraged, and an average value may be taken as the value of the soundleakage. These measurement and calculation methods may be adjusted bythose skilled in the art according to actual conditions, which are notlimited herein.

According to FIG. 2, it can be concluded that in the high-frequency band(e.g., a relatively high frequency band determined according to thefrequency division point), the dual-point sound source may have arelatively weak capability to reduce sound leakage, and in thelow-frequency band (e.g., a relatively low frequency band determinedaccording to the frequency division point), the dual-point sound sourcemay have a relatively strong capability to reduce sound leakage. At acertain sound frequency, the amplitudes, phase differences, etc., of thetwo point sound sources of the dual-point radiation source may bedifferent, and the capability of the two point sound sources of thedual-point radiation source to reduce sound leakage may be different,and the difference between a volume of the heard sound and a volume ofthe leakage sound may be different. For a better description, the curveof the far-field leakage as a function of the distance between the twopoint sound sources may be described with reference to FIGS. 3A and 3B.

FIG. 3A and FIG. 3B are graphs illustrating changes of a volume of thenear-field sound and a volume of the far-field leakage with a distanceof two point sound sources of a dual-point sound source according tosome embodiments of the present disclosure. FIG. 3B is the graph whichis generated by performing a normalization on the graph in FIG. 3A. Asshown in FIG. 3A, a solid line represents a variation curve of a hearingsound of the dual-point sound source with the distance between the twopoint sound sources of the dual-point sound source, and a dotted linerepresents a variation curve of a leakage sound of the dual-point soundsource with the distance between the two point sound sources of thedual-point sound source. The abscissa represents a distance ratio d/d0of the distance d between the two point sound sources of the dual-pointsound source to a reference distance d0. The ordinate represents a soundvolume (the unit is dB). The distance ratio d/d0 may reflect a change ofthe distance between the two point sound sources of the dual-point soundsource. In some embodiments, the reference distance d0 may be determinedwithin a specific range. For example, d0 may be a specific value in therange of 2.5 millimeters-10 millimeters. Merely by way of example, d0may be 5 millimeters. In some embodiments, the reference distance d0 maybe determined based on a hearing position. For example, a distancebetween the hearing position to a nearest point sound source among thetwo point sound sources of the dual-point sound source may be regardedas the reference distance d0. It should be known that the referencedistance d0 may be determined as any other suitable values according tothe actual conditions, which is not limited herein. Merely by way ofexample, in FIG. 3A, d0 may be 5 millimeters as the reference value forthe change of the distance between the two point sound sources of thedual-point sound source.

When the sound frequency is constant, a volume of the hearing sound anda volume of the leakage sound of the dual-point sound source mayincrease as the distance between the two point sound sources of thedual-point sound source increases. When the distance ratio d/d0 is lessthan a ratio threshold, as the distance between the two point soundsources of the dual-point sound source increases, the increment of thevolume of the hearing sound may be greater than the increment of thevolume of the leakage sound. That is, the increment of the volume of thehearing sound may be more significant than that of the volume of theleakage sound. For example, as shown in FIG. 3A, when the distance ratiod/d0 is 2, a difference between the volume of the hearing sound and thevolume of the leakage sound may be about 20 dB. When the distance ratiod/d0 is 4, the difference between the volume of the hearing sound andthe volume of the leakage sound may be about 25 dB. In some embodiments,when the distance ratio d/d0 reaches the ratio threshold, a ratio of thevolume of the hearing sound and the volume of the leakage sound mayreach a maximum value, and as the distance of the two point soundsources of the dual-point sound source further increases, the curve ofthe volume of the hearing sound and the curve of the volume of theleakage sound may gradually go parallel. That is, the increment of thevolume of the hearing sound and the increment of the volume of theleakage sound may be the same (or substantially same). For example, asshown in FIG. 3B, when the distance ratio d/d0 is 5, 6, or 7, thedifference between the volume of the hearing sound and the volume of theleakage sound may be the same (or substantially same), which may beabout 25 dB. That is, the increment of the volume of the hearing soundmay be the same as the increment of the volume of the leakage sound. Insome embodiments, the ratio threshold of the distance ratio d/d0 of thedual-point sound source may be in the range of 0-7, 0.5-4.5, 1-4, etc.

In some embodiments, the ratio threshold may be determined based on thechange of the difference between the volume of the hearing sound and thevolume of the leakage sound of the dual-point sound source in FIG. 3A.For example, the ratio of the volume of the hearing sound to the volumeof the leakage sound may be determined as the ratio threshold when amaximum difference between the volume of the hearing sound and thevolume of the leakage sound is reached. As shown in FIG. 3B, when thedistance ratio d/d0 is less than the ratio threshold (e.g., 4), as thedistance between the two point sound sources of the dual-point soundsource increases, a normalized curve of a hearing sound may show anupward trend (e.g., a slope of the normalized curve is greater than 0).That is, the increment of the volume of the hearing sound may be greaterthan the increment of the volume of the leakage sound. When the distanceratio d/d0 is greater than the ratio threshold, as the distance betweenthe two point sound sources of the dual-point sound source increases,the slope of the normalized curve of the hearing sound may graduallyapproach 0. The normalized curve of the hearing sound may be parallel tothe normalized curve of the leakage sound. That is, as the distancebetween the two point sound sources of the dual-point sound sourceincreases, the increment of the volume of the hearing sound may be nolonger greater than the increment of the volume of the leakage sound.

Based on the description mentioned above, it can be seen that when thehearing position is constant and the parameters of the dual-point soundsource may be adjusted by certain means, thereby achieving significantlyincreasing the volume of the near-field sound and slightly increasingthe volume of the far-field leakage (that is, the increment of thevolume of the near-field sound is greater than the increment of thevolume of the far-field leakage). For example, two or more of dual-pointsound sources (e.g., a high-frequency dual-point sound source and alow-frequency dual-point sound source) may be disposed, the distancebetween two point sound sources of each of the dual-point sound sourcesmay be adjusted by a certain means, and the distance between two pointsound sources of the high-frequency dual-point sound source may be lessthan the distance between two point sound sources of the low-frequencydual-point sound source. Due to the low-frequency dual-point soundsource may have a small sound leakage (i.e., the low-frequencydual-point sound source may have a relatively strong capability toreduce the sound leakage), and the high-frequency dual-point soundsource may have a relatively great sound leakage (i.e., thehigh-frequency dual-point sound source may have a relatively weakcapability to reduce the sound leakage). The volume of the hearing soundmay be significantly greater than the volume of the leakage sound whenthe distance between the two point sound sources of the dual-point soundsource in the high-frequency band is relatively small, thereby reducingthe sound leakage.

In the embodiments of the present disclosure, a distance may be betweentwo guiding holes corresponding to each set of acoustic drivers, and thedistance may affect the volume of the near-field sound transmitted bythe acoustic output device to the user's ears and the volume of thefar-field leakage transmitted by the acoustic output device to theenvironment. In some embodiments, when the distance between the guidingholes corresponding to a high-frequency acoustic driver is less than thedistance between the guiding holes corresponding to a low-frequencyacoustic driver, the volume of the hearing sound may be increased andthe volume of the leakage sound may be reduced, thereby preventing thesound from being heard by others near the user of the acoustic outputdevice. According to the above descriptions, the acoustic output devicemay be effectively used as an open binaural earphone even in arelatively quiet environment.

FIG. 4 is a schematic diagram illustrating an exemplary acoustic outputdevice according to some embodiments of the present disclosure. As shownin FIG. 4, an acoustic output device 100 may include an electronicfrequency division unit 110, an acoustic driver 140, an acoustic driver150, an acoustic route 145, an acoustic route 155, at least two firstsound guiding holes 147, and at least two second sound guiding holes157. In some embodiments, the acoustic output device 100 may furtherinclude a controller (not shown in the figure). The electronic frequencydivision unit 110, as part of the controller, may be configured togenerate electrical signals that are input into different acousticdrivers. The connection between different components in the acousticoutput device 100 may be wired or wireless. For example, the electronicfrequency division unit 110 may send signals to the acoustic driver 140and/or the acoustic driver 150 via a wired transmission manner or awireless transmission manner.

The electronic frequency division unit 110 may divide a frequency of asource signal. The source signal may come from one or more sound sourceapparatuses (e.g., a memory storing audio data) integrated into theacoustic output device 100. The source signal may also be an audiosignal that the acoustic output device 100 received by a wired orwireless means. In some embodiments, the electronic frequency divisionunit 110 may decompose the input source signal into two or morefrequency-divided signals containing different frequencies. For example,the electronic frequency division unit 110 may decompose the sourcesignal into a first frequency-divided signal (or frequency-dividedsignal 1) with high-frequency sound and a second frequency-dividedsignal (or frequency-divided signal 2) with low-frequency sound. Forconvenience, a frequency-divided signal with high-frequency sound may bereferred to as a high-frequency signal, and a frequency-divided signalwith low-frequency sound may be directly referred to as a low-frequencysignal. The low-frequency signal may refer to a voice signal withfrequencies in a first frequency range. The high-frequency signal mayrefer to a voice signal with frequencies in a second frequency range.

For the purposes of illustration, a low-frequency signal described insome embodiments of the present disclosure may refer to a voice signalwith a frequency in a first frequency range with relatively lowfrequencies, and a high-frequency signal may refer to a voice signalwith a frequency in a second frequency range with relatively greatfrequencies. The first frequency range and the second frequency rangemay include or not include overlapping frequency ranges, and the secondfrequency range may include frequencies higher than the frequencies inthe first frequency range. Merely by way of example, the first frequencyrange may include frequencies below a first frequency threshold, and thesecond frequency range may include frequencies above a second frequencythreshold. The first frequency threshold may be lower than the secondfrequency threshold, equal to the second frequency threshold, or higherthan the second frequency threshold. For example, the first frequencythreshold may be smaller than the second frequency threshold (e.g., thefirst frequency threshold may be 600 Hz, and the second frequencythreshold may be 700 Hz), which may indicate that there is no overlapbetween the first frequency range and the second frequency range. Asanother example, the first frequency threshold may be equal to thesecond frequency (e.g., both the first frequency threshold and thesecond frequency threshold may be 650 Hz or other frequency values). Asyet another example, the first frequency threshold may be greater thanthe second frequency threshold, which may indicate that there is anoverlap between the first frequency range and the second frequencyrange. In this case, a difference between the first frequency thresholdand the second frequency threshold may not exceed a third frequencythreshold. The third frequency threshold may be a value, for example, 20Hz, 50 Hz, 100 Hz, 150 Hz, 200 Hz, etc., or may be a value related tothe first frequency threshold and/or the second frequency threshold(e.g., 5%, 10%, 15%, etc., of the first frequency threshold). The thirdfrequency threshold may be a value determined by a user according to theactual needs, which is not limited herein. It should be known that thefirst frequency threshold and the second frequency threshold may bedetermined according to different situations, which are limited herein.

In some embodiments, the electronic frequency division unit 110 mayinclude a frequency divider 115, a signal processor 120, and a signalprocessor 130. The frequency divider 115 may be used to decompose thesource signal into two or more frequency-divided signals containingdifferent frequency components, for example, a frequency-divided signal1 with high-frequency sound components and a frequency-divided signal 2with low-frequency sound components. In some embodiments, the frequencydivider 115 may be an electronic device that may implement the signaldecomposition function, including but not limited to one of a passivefilter, an active filter, an analog filter, a digital filter, or anycombination thereof. In some embodiments, the frequency divider 115 maydivide the sound source signal based on one or more frequency divisionpoints. A frequency division point refers to a signal frequency thatdistinguishes the first frequency range from the second frequency range.For example, when the first frequency range and the second frequencyrange include an overlapping frequency range, the frequency divisionpoint may be a feature point within the overlapping frequency range(e.g., a low-frequency boundary point, a high-frequency boundary point,a center frequency point, etc., of the overlapping frequency range). Insome embodiments, the frequency division point may be determinedaccording to a relationship (e.g., the curves shown in FIG. 2, FIG. 3A,or 3B) between a frequency and the sound leakage of the acoustic outputdevice. For example, considering that the leakage sound of the acousticoutput device may vary with a change of the frequency, a frequency pointcorresponding to the volume of the leakage sound that meets a certaincondition may be selected as the frequency division point, for example,1000 Hz shown in FIG. 2. More descriptions regarding the change of theleakage sounds with the frequency may be found elsewhere in the presentdisclosure. See, e.g., FIG. 2 and the relevant descriptions thereof. Insome alternative embodiments, a user may directly determine a specificfrequency as the frequency division point. For example, considering thatthe frequency range of sounds that a human ear can hear is 20 Hz-20 kHz,the user may select a frequency point in this range as the frequencydivision point. Merely by way of example, the frequency division pointmay be 600 Hz, 800 Hz, 1000 Hz, 1200 Hz, etc. In some embodiments, thefrequency division point may be determined according to performance ofthe acoustic driver. For example, considering that the low-frequencyacoustic driver and the high-frequency acoustic driver may havedifferent frequency response curves, the frequency division point may bedetermined in a frequency range above ½ of an upper limiting frequencyof the low-frequency acoustic driver and below 2 times of a low limitingfrequency of the high-frequency acoustic driver. As another example, thefrequency division point may be determined in a frequency range above ⅓of the upper limiting frequency of the low-frequency acoustic driver andbelow 1.5 times of the low limiting frequency of the high-frequencyacoustic driver. In some embodiments, in the overlapping frequencyrange, a position relationship between point sound sources may affectthe volume produced by the acoustic output device in the near-field andthe far-field. More descriptions regarding the effect of the positionrelationship between point sound sources on the volume produced by theacoustic output device in the near-field and the far-field may be foundin International application No. PCT/CN2019/130886, filed on Dec. 31,2019, the entire contents of which are hereby incorporated by reference.

The signal processors 120 and 130 may respectively process thefrequency-divided signals to meet requirements of subsequent soundoutput. In some embodiments, the signal processor 120 or 130 may includeone or more signal processing units. For example, the signal processormay include, but not limited to, an amplifier, an amplitude modulator, aphase modulator, a delayer, or a dynamic gain controller, or the like,or any combination thereof. Merely by way of example, the processing ofthe voice signal by the signal processor 120 and/or the signal processor130 may include adjusting the amplitude corresponding to somefrequencies in the voice signal. Specifically, when the first frequencyrange has an overlapping frequency range with the second frequencyrange, the signal processors 120 and 130 may adjust an intensity of thevoice signal corresponding to the frequency in the overlapping frequencyrange (e.g., reduce the amplitude of a signal corresponding to afrequency in the overlapping frequency range), thereby avoidingexcessive volume in the overlapping frequency range in the subsequentoutput sound caused by superposition of multiple voice signals.

After the processing operations are performed by the signal processor120 or the signal processor 130, the frequency-divided signals may betransmitted to the acoustic drivers 140 and 150, respectively. In someembodiments, the voice signal transmitted to the acoustic driver 140 maybe a voice signal including a relatively low frequency range (e.g., thefirst frequency range), and the acoustic driver 140 may also be referredto as a low-frequency acoustic driver. The voice signal transmitted intothe acoustic driver 150 may be a voice signal including a relativelyhigh frequency range (e.g., the second frequency range), and theacoustic driver 150 may also be referred to as a high-frequency acousticdriver. The acoustic driver 140 and the acoustic driver 150 may convertthe voice signals into a low-frequency sound and a high-frequency sound,respectively, then propagate the converted sound outwards.

In some embodiments, the acoustic driver 140 may be acoustically coupledto at least two first sound guiding holes (e.g., two first sound guidingholes 147) (e.g., connected to the two first sound guiding holes 147 viatwo acoustic routes 145 respectively). Then the acoustic driver 140 maypropagate the sound through the at least two first sound guiding holes.The acoustic driver 150 may be acoustically coupled to at least twosecond sound guiding holes (e.g., two second sound guiding holes 157)(e.g., connected to the two second sound guiding holes 157 via twoacoustic routes 155, respectively). Then the acoustic driver 150 maypropagate the sound through the at least two second sound guiding holes.Each of the sound guiding holes (e.g., the at least two first soundguiding holes or the at least two second sound guiding holes) may be arelatively small hole formed on the acoustic output device with aspecific opening and allow the sound to pass through. The shape of thesound guiding hole may include but is not limited to a circle shape, anoval shape, a square shape, a trapezoid shape, a rounded quadrilateralshape, a triangle shape, an irregular shape, or the like, or anycombination thereof. In addition, a count of the sound guiding holescoupled to the acoustic driver 140 or 150 may be not limited to two,which may be determined based on actual needs, for example, 3, 4, 6, orthe like.

In some embodiments, in order to reduce the far-field leakage of theacoustic output device 100, the acoustic driver 140 may be used togenerate low-frequency sounds with equal (or approximately equal)amplitude and opposite (or approximately opposite) phases at the atleast two first sound guiding holes, respectively. The acoustic driver150 may be used to generate high-frequency sounds with equal (orapproximately equal) amplitude and opposite (or approximately opposite)phases at the at least two second sound guiding holes, respectively. Inthis way, the far-field leakage of low-frequency sounds (orhigh-frequency sounds) may be reduced according to the principle ofacoustic interference cancellation. In some embodiments, according toFIG. 2, FIG. 3A, and FIG. 3B, further considering that a wavelength ofthe low-frequency sound is longer than that of the high-frequency sound,and in order to reduce the interference cancellation of the sound in thenear-field (e.g., a position of the user's ear), a distance between thetwo first sound guiding holes and a distance between the two secondsound guiding holes may be set to be different values. For example,assuming that there is a first distance between the two first guidingholes and a second distance between the two second guiding holes, thefirst distance may be longer than the second distance. In someembodiments, the first distance and the second distance may be arbitraryvalues. Merely by way of example, the first distance may be less than orequal to 40 millimeters, for example, the first distance may be in therange of 20 millimeters-40 millimeters. The second distance may be lessthan or equal to 12 millimeters, and the first distance may be longerthan the second distance. In some embodiments, the first distance may begreater than or equal to 12 millimeters, and the second distance may beless than or equal to 7 mm, for example, in the range of 3 millimeters-7millimeters. In some embodiments, the first distance may be 30millimeters, and the second distance may be 5 millimeters. In someembodiments, the first distance may be at least twice, 3 times, 5 times,etc. of the second distance.

As shown in FIG. 4, the acoustic driver 140 may include a transducer143. The transducer 143 may transmit sound to the first sound guidingholes 147 through the acoustic route 145. The acoustic driver 150 mayinclude a transducer 153. The transducer 153 may transmit sound to thesecond sound guiding holes 157 through the acoustic route 155. In someembodiments, the transducer (e.g., the transducer 143 or the transducer153) may include, but not be limited to, a transducer of agas-conducting acoustic output device, a transducer of a bone-conductingacoustic output device, a hydroacoustic transducer, an ultrasonictransducer etc. In some embodiments, the transducer may be of a movingcoil type, a moving iron type, a piezoelectric type, an electrostatictype, or a magneto strictive type, or the like, or any combinationthereof.

In some embodiments, the acoustic drivers (e.g., the low-frequencyacoustic driver 140, the high-frequency acoustic driver 150) may includetransducers with different properties or numbers. For example, each ofthe low-frequency acoustic driver 140 and the high-frequency acousticdriver 150 may include a transducer (e.g., a low-frequency speaker unitand a high-frequency speaker unit) having different frequency responsecharacteristics. As another example, the low-frequency acoustic driver140 may include two transducers (e.g., two low-frequency speaker units),and the high-frequency acoustic driver 150 may include two transducers153 (e.g., two high-frequency speaker units).

In some alternative embodiments, the acoustic output device 100 maygenerate sound with different frequency ranges by other means, such astransducer frequency division, acoustic route frequency division, or thelike. When the acoustic output device 100 uses a transducer or anacoustic route to divide the sound, the electronic frequency divisionunit 110 (a part inside the dotted box) may be omitted, and the voicesignal may be transmitted to the acoustic driver 140 and the acousticdriver 150.

In some alternative embodiments, the acoustic output device 100 may usea transducer to achieve signal frequency division, the acoustic driver140 and the acoustic driver 150 may convert the input sound sourcesignal into a low-frequency sound and a high-frequency sound,respectively. Specifically, through the transducer 143 (such as alow-frequency speaker), the low-frequency acoustic driver 140 mayconvert the voice signal into the low-frequency sound with low-frequencycomponents. In some embodiments, at least two first acoustic routes maybe formed between the at least one low-frequency acoustic driver and theat least two first guiding holes. The low-frequency sound may betransmitted to the at least two first sound guiding holes 147 along atleast two different acoustic routes (i.e., at least two first acousticroutes). Then the low-frequency sound may be propagated outwards throughthe first sound guiding holes 147. Through the transducer 153 (such as ahigh-frequency speaker), the high-frequency acoustic driver 150 mayconvert the voice signal into the high-frequency sound withhigh-frequency components. In some embodiments, at least two secondacoustic routes may be formed between the at least one high-frequencyacoustic driver and the at least two second guiding holes. Thehigh-frequency sound may be transmitted to the at least two second soundguiding holes 157 along at least two different acoustic routes (i.e.,the at least two second acoustic routes). Then the high-frequency soundmay be propagated outwards through the second sound guiding holes 157.In some embodiments, the at least two first acoustic routes and the atleast two second acoustic routes may have different frequency selectioncharacteristics. As used herein, the frequency selection characteristicof an acoustic route refers to that a sound signal with a predeterminedfrequency range may be passed through the acoustic route. The frequencyselection characteristic of an acoustic route may include thepredetermined frequency range within which a sound can pass through theacoustic route. For example, a sound with low-frequency componentswithin a first frequency range may be passed through the at least twofirst acoustic routes and a sound with high-frequency components withina second frequency range may be passed through the at least two secondacoustic routes. The first frequency range may include frequencies lessthan frequencies in the second frequency range. In some embodiments, thefirst frequency range may include a maximum frequency that is less thanor equal to the minimum frequency in the second frequency range. In someembodiments, the first frequency range may include the maximum frequencythat exceeds the minimum frequency in the second frequency range andless than the maximum frequency in the second frequency range. In someembodiments, the at least two first acoustic routes may have differentfrequency selection characteristics. In some embodiments, the at leasttwo first acoustic routes may have the same frequency selectioncharacteristic. In some embodiments, the at least two second acousticroutes may have different frequency selection characteristics. In someembodiments, the at least two second acoustic routes may have the samefrequency selection characteristic.

In some alternative embodiments, an acoustic route (e.g., the acousticroute 145 and the acoustic route 155) connecting a transducer and soundguiding holes may affect the nature of the transmitted sound. Forexample, an acoustic route may attenuate or change a phase of thetransmitted sound to some extent. In some embodiments, an acoustic routemay include a sound tube, a sound cavity, a resonance cavity, a soundhole, a sound slit, or a tuning network, or the like, or any combinationthereof. In some embodiments, the acoustic route (e.g., at least one ofthe at least two first acoustic routes, at least one of the at least twosecond acoustic routes, etc.) may also include an acoustic resistancematerial, which may have a specific acoustic impedance. For example, theacoustic impedance may be in the range of 5MKS Rayleigh to 500MKSRayleigh. The acoustic resistance materials may include, but not belimited to, plastic, textile, metal, permeable material, woven material,screen material or mesh material, porous material, particulate material,polymer material, or the like, or any combination thereof. By settingthe acoustic routes with different acoustic impedances, the acousticoutput of the transducer may be acoustically filtered, such that thesounds output through different acoustic routes may have differentfrequency components.

In some alternative embodiments, the acoustic output device 100 mayutilize acoustic routes to achieve signal frequency division.Specifically, the source signal may be input into a specific acousticdriver and converted into a sound containing high and low-frequencycomponents. The voice signal may be propagated along acoustic routeshaving different frequency selection characteristics. For example, thevoice signal may be propagated along the acoustic route with a low-passcharacteristic to the corresponding sound guiding hole to generatelow-frequency sound. In this process, the high-frequency sound may beabsorbed or attenuated by the acoustic route with a low-passcharacteristic. Similarly, the voice signal may be propagated along theacoustic route with a high-pass characteristic to the correspondingsound guiding hole to generate a high-frequency sound. In this process,the low-frequency sound may be absorbed or attenuated by the acousticroute with the high-pass characteristic.

In some embodiments, the acoustic output device 100 may include acontroller (not shown in figure). The controller may cause thelow-frequency acoustic driver 140 to output a sound in the firstfrequency range (i.e., low-frequency sound), and cause thehigh-frequency acoustic driver 150 to output a sound in the secondfrequency range (i.e., high-frequency sound). In some embodiments, theacoustic output device 100 may also include a supporting structure. Thesupporting structure may be used to support the acoustic driver (such asthe high-frequency acoustic driver 150, the low-frequency acousticdriver 140, etc.), so that the sound guiding holes corresponding to theacoustic driver is positioned away from the user's ear. In someembodiments, the sound guiding holes (e.g., the at least two secondguiding holes) acoustically coupled with the high-frequency acousticdriver 150 may be located closer to an expected position of the user'sear (e.g., the ear canal entrance), while the sound guiding holes (e.g.,the at least two first guiding holes) acoustically coupled with thelow-frequency acoustic driver 140 may be located further away from theexpected position. For example, a distance between the sound guidingholes (e.g., the at least two second guiding holes) acoustically coupledwith the high-frequency acoustic driver 150 and the expected position ofthe user's ear may be less than a first distance threshold, and adistance between the sound guiding holes (e.g., the at least firstsecond guiding holes) acoustically coupled with the low-frequencyacoustic driver 140 and the expected position of the user's ear may begreater than a second distance threshold. The first distance thresholdand/or the second distance threshold may be determined according to anactual need. The first distance threshold may be less than the seconddistance threshold.

In some embodiments, the supporting structure may be used to package theacoustic driver. The supporting structure of the packaged acousticdriver may be a housing made of various materials such as plastic,metal, tape, etc. The housing may encapsulate the acoustic driver andform a front chamber and a rear chamber corresponding to the acousticdriver. For example, the low-frequency acoustic driver may beencapsulated by a first housing, and the first housing may define afront chamber and a rear chamber of the low-frequency acoustic driver.As another example, the high-frequency acoustic driver may beencapsulated by a second housing, and the second housing may define afront chamber and a rear chamber of the high-frequency acoustic driver.In some embodiments, the second housing may be the same as or differentfrom the first housing. The front chamber may be acoustically coupled toone of the at least two sound guiding holes. The rear chamber may beacoustically coupled to the other of the at least two sound guidingholes. For example, the front chamber of the low-frequency acousticdriver 140 may be acoustically coupled to one of the at least two firstsound guiding holes 147. The rear chamber of the low-frequency acousticdriver 140 may be acoustically coupled to the other of the at least twofirst sound guiding holes 147. The front chamber of the high-frequencyacoustic driver 150 may be acoustically coupled to one of the at leasttwo second sound guiding holes 157. The rear chamber of thehigh-frequency acoustic driver 150 may be acoustically coupled to theother of the at least two second sound guiding holes 157. As usedherein, a front chamber of a housing refers to a space (also referred toas a route) between the acoustic driver and one of the at least twosound guiding holes acoustically coupled to the acoustic driver, whichis encapsulated by the housing. A rear chamber of the housing refers toa route between the acoustic driver and the other of the at least twosound guiding holes. For example, the front chamber of the low-frequencyacoustic driver 140 may be a space between the low-frequency acousticdriver 140 and one of the first sounding guiding holes 147, which isencapsulated by the housing (e.g., the first housing). The rear chamberof the low-frequency acoustic driver 140 may be a space between thelow-frequency acoustic driver 140 and the other of the first soundingguiding holes 147, which is encapsulated by the housing (e.g., the firsthousing). As another example, the front chamber of the high-frequencyacoustic driver 150 may be a space between the high-frequency acousticdriver 150 and one of the first sounding guiding holes 157, which isencapsulated by the housing (e.g., the second housing). The rear chamberof the high-frequency acoustic driver 150 may be a space between thehigh-frequency acoustic driver 150 and the other of the first soundingguiding holes 157, which is encapsulated by the housing (e.g., thesecond housing). In some embodiments, the sound guiding holes (e.g., thefirst sound guiding holes 147 and the second sound guiding holes 157)may be disposed on the housing.

The above descriptions of the acoustic output device 100 may be merelysome examples. Those skilled in the art may make adjustments and changesto the structure, quantity, etc. of the acoustic driver, which is notlimiting in the present disclosure. In some embodiments, the acousticoutput device 100 may include any number of the acoustic driverstructures. For example, the acoustic output device 100 may include twosets of the high-frequency acoustic drivers 150 and two sets of thelow-frequency acoustic drivers 140, or one set of the high-frequencyacoustic drives 150 and two sets of the low-frequency acoustic drivers140, and these high-frequency/low-frequency drivers may be used togenerate a sound in a specific frequency range. As another example, theacoustic driver 140 and/or the acoustic driver 150 may include anadditional signal processor. The signal processor may have the same ordifferent structural components as the signal processor 120 or thesignal processor 130.

It should be noted that the acoustic output device and its modules areshown in FIG. 4 may be implemented in various ways. For example, in someembodiments, the system and the modules may be implemented by hardware,software, or a combination of both. The hardware may be implemented by adedicated logic. The software may be stored in the storage which may beexecuted by a suitable instruction execution system, for example, amicroprocessor or dedicated design hardware. It will be appreciated bythose skilled in the art that the above methods and systems may beimplemented by computer-executable instructions and/or embedded in thecontrol codes of a processor. For example, the control codes may beprovided by a medium such as a disk, a CD, or a DVD-ROM, a programmablememory device, such as a read-only memory (e.g., firmware), or a datacarrier such as an optical or electric signal carrier. The system andthe modules in the present disclosure may be implemented not only by ahardware circuit in a programmable hardware device in an ultra-largescale integrated circuit, a gate array chip, a semiconductor such alogic chip or a transistor, a field programmable gate array, or aprogrammable logic device. The system and the modules in the presentdisclosure may also be implemented by software to be performed byvarious processors, and further also by a combination of hardware andsoftware (e.g., firmware).

It should be noted that the above description of the acoustic outputdevice 100 and its components is only for the convenience ofdescription, and not intended to limit the scope of the presentdisclosure. For example, the signal processor 120 or the signalprocessor 130 may be a part independent of the electronic frequencydivision unit 110. Those modifications may fall within the scope of thepresent disclosure.

FIG. 5 is a schematic diagram illustrating an exemplary acoustic outputdevice according to some embodiments of the present disclosure. For thepurposes of illustration, an outward propagating sound formed by thesame transducer coupled with different sound guiding holes may bedescribed as an example. In FIG. 5, each transducer may have a frontside and a rear side, and a corresponding front chamber (i.e., a firstacoustic route) and a rear chamber (i.e., a second acoustic route) mayexist on the front side or the rear side of the transducer,respectively. In some embodiments, the front chamber and the rearchamber may have the same or the substantially same equivalent acousticimpedance, such that the transducers may be loaded symmetrically. Thesymmetrical load of the transducer may form sound sources satisfy anamplitude and phase relationship at different sound guiding holes (suchas the “two point sound sources” having the same amplitude and oppositephases as described above), such that a specific sound field may beformed in high-frequency and/or low-frequency (e.g., a near-field soundmay be enhanced and a far-field leakage may be suppressed).

As shown in FIG. 5, the acoustic driver (e.g., the acoustic driver 140or 150) may include transducers, and acoustic routes and sound guidingholes connected to the transducer. In order to describe the actualapplication scenarios of the acoustic output device 300 more clearly, aposition of the user's ear E may also be shown in FIG. 5 for theexplanation. FIG. (a) in FIG. 5 illustrates an application scenario ofthe acoustic driver 140. The acoustic driver 140 may include atransducer 143, and the transducer 143 may be coupled with two firstsound guiding holes 147 through an acoustic route 145. FIG. (b) in FIG.5 illustrates an application scenario of the acoustic driver 150. Theacoustic driver 150 may include a transducer 153, and the transducer 153may be coupled with two second sound guiding holes 157 through anacoustic route 155.

The transducer 143 or 153 may vibrate under the driving of an electricsignal, and the vibration may generate sound with equal amplitudes andopposite phases (180 degrees inversion). The type of transducer mayinclude, but not limited to, an air conduction speaker, a boneconduction speaker, a hydroacoustic transducer, an ultrasonictransducer, or the like, or any combination thereof. The transducer maybe of a moving coil type, a moving iron type, a piezoelectric type, anelectrostatic type, a magneto strictive type, or the like, or anycombination thereof. In some embodiments, the transducer 143 or 153 mayinclude a vibration diaphragm, which may vibrate when driven by anelectrical signal, and the front and rear sides of the vibrationdiaphragm may simultaneously output a normal-phase sound and areverse-phase sound. In FIG. 5, “+” and “−” may be used to exemplifysounds with different phases, wherein “+” may represent a normal-phasesound, and “−” may represent a reverse-phase sound.

In some embodiments, the transducer may be encapsulated by a housing(e.g., a supporting structure), and the interior of the housing may beprovided with sound channels connected to the front and rear sides ofthe transducer, respectively, thereby forming an acoustic route. Forexample, the front cavity of the transducer 143 may be coupled to one ofthe two first sound guiding holes 147 through a first acoustic route(i.e., the first half of the acoustic route 145), and the rear cavity ofthe transducer 143 may acoustically be coupled to the other soundguiding hole of the two first sound guiding holes 147 through a secondacoustic route (i.e., the second half of the acoustic route 145).Normal-phase sound and reverse-phase sound that output from thetransducer 143 may be output from the two first sound guiding holes 147,respectively. As another example, the front cavity of the transducer 153may be coupled to one of the two sound guiding holes 157 through a thirdacoustic route (i.e., the first half of the acoustic route 155), and therear cavity of the transducer 153 may be coupled to another soundguiding hole of the two second sound guiding holes 157 through a fourthacoustic route (i.e., the second half of the acoustic route 155). Thenormal-phase sound and the reverse-phase sound output from thetransducer 153 may be output from the two second sound guiding holes157, respectively.

In some embodiments, acoustic routes may affect the nature of thetransmitted sound. For example, an acoustic route may attenuate orchange the phase of the transmitted sound to some extent. In someembodiments, the acoustic route may be composed of one of a sound tube,a sound cavity, a resonance cavity, a sound hole, a sound slit, a tuningnetwork, or the like, or any combination of. In some embodiments, theacoustic route may also include an acoustic resistance material, whichmay have a specific acoustic impedance. For example, the acousticimpedance may be in the range of 5MKS Rayleigh to 500MKS Rayleigh. Insome embodiments, the acoustic resistance material may include, but notlimited to, one of plastics, textiles, metals, permeable materials,woven materials, screen materials, and mesh materials, or the like, orany combination of. In some embodiments, in order to prevent the soundtransmitted by the acoustic driver's front chamber and rear chamber frombeing disturbed (or the same change caused by disturbance), the frontchamber and rear chamber corresponding to the acoustic driver may be setto have approximately the same equivalent acoustic impedance. Forexample, the same acoustic resistance material, the sound guiding holeswith the same size or shape, etc., may be used.

A distance between the two first sound guiding holes 147 of thelow-frequency acoustic driver may be expressed as d1 (i.e., a firstdistance). The distance between the two second sound guiding holes 157of the high-frequency acoustic driver may be expressed as d2 (i.e., asecond distance). By setting the distance between the sound guidingholes corresponding to the low-frequency acoustic driver and thehigh-frequency acoustic driver, a higher sound volume output in thelow-frequency band and a stronger ability to reduce the sound leakage inthe high-frequency band may be achieved. For example, the distancebetween the two first sound guiding holes 147 is greater than thedistance between the two second sound guiding holes 157 (i.e., d₁>d₂).

In some embodiments, the transducer 143 and the transducer 153 may behoused together in a housing of an acoustic output device, and be placedin isolation in a structure of the housing.

In some embodiments, the acoustic output device 300 may include multiplesets of high-frequency acoustic drivers and low-frequency acousticdrivers. For example, the acoustic output device 300 may include a groupof high-frequency acoustic drivers and a group of low-frequency acousticdrivers for simultaneously outputting sound to the left and/or rightears. As another example, the acoustic output device may include twogroups of high-frequency acoustic drivers and two groups oflow-frequency acoustic drivers, wherein one group of high-frequencyacoustic drivers and one group of low-frequency acoustic drivers may beused to output sound to a user's left ear, and the other set ofhigh-frequency acoustic drivers and low-frequency acoustic drivers maybe used to output sound to a user's right ear.

In some embodiments, the high-frequency acoustic driver and thelow-frequency acoustic driver may be configured to have differentpowers. In some embodiments, the low-frequency acoustic driver may beconfigured to have a first power, the high-frequency acoustic driver maybe configured to have a second power, and the first power may be greaterthan the second power. In some embodiments, the first power and thesecond power may be arbitrary values.

FIG. 6A is a schematic diagram illustrating a process for sound outputaccording to some embodiments of the present disclosure. FIG. 6B is aschematic diagram illustrating another process for sound outputaccording to some embodiments of the present disclosure.

In some embodiments, the acoustic output device may generate sounds inthe same frequency range through two or more transducers, and the soundsmay propagate outwards through different sound guiding holes. In someembodiments, different transducers may be controlled by the same ordifferent controllers, respectively, and may produce sounds that satisfycertain phase and amplitude conditions (e.g., sounds with the sameamplitude but opposite phases, sounds with different amplitudes andopposite phases, etc.). For example, the controller may make theelectrical signals input to the two low-frequency transducers of theacoustic driver have the same amplitude and opposite phases. In thisway, when a sound is formed, the two low-frequency transducers mayoutput low-frequency sounds with the same amplitude but opposite phases.

Specifically, the two transducers in the acoustic driver (such as thelow-frequency acoustic driver 140 and the high-frequency acoustic driver150) may be arranged side by side in an acoustic output device, one ofwhich may be used to output normal-phase sound, and the other may beused to output reverse-phase sound. As shown in FIG. 6A, the acousticdriver 140 on the right may include two transducers 143, two acousticroutes 145, and two first sound guiding holes 147. The acoustic driver150 on the left may include two transducers 153, two acoustic routes155, and two second sound guiding holes 157. Driven by electricalsignals with opposite phases, the two transducers 143 may generate a setof low-frequency sounds with opposite phases (180 degrees inversion).One of the two transducers 143 may output normal-phase sound (such asthe transducer located below), and the other may output reverse-sound(such as the transducer located above). The two sets of low-frequencysounds with opposite phases may be transmitted to the two first soundguiding holes 147 along the two acoustic routes 145, respectively, andpropagate outwards through the two first sound guiding holes 147.Similarly, driven by electrical signals with opposite phases, the twotransducers 153 may generate a set of high-frequency sounds withopposite phases (180 degrees inversion). One of the two transducers 153may output normal-phase high-frequency sound (such as the transducerlocated below), and the other may output a reverse-phase high-frequencysound (such as the transducer located above). The high-frequency soundwith opposite phases may be transmitted to the two second sound guidingholes 157 along the two acoustic routes 155, respectively, and propagateoutwards through the two second sound guiding holes 157.

In some embodiments, the two transducers in the acoustic driver (e.g.,the low-frequency acoustic driver 140 and the high-frequency acousticdriver 150) may be arranged relatively close to each other along thesame straight line, and one of them may be used to output a normal-phasesound and the other may be used to output a reverse-sound. As shown inFIG. 6B, the left side may be the acoustic driver 140, and the rightside may be the acoustic driver 150. The two transducers 143 of theacoustic driver 140 may generate a set of low-frequency sounds of equalamplitude and opposite phases under the control of the controller,respectively. One of the transducers may output normal low-frequencysound, and transmit the normal low-frequency sound along a firstacoustic route to a first sound guiding hole. The other transducer mayoutput reverse-phase low-frequency sound, and transmit the reverse-phaselow-frequency sound along the second acoustic route to another firstsound guiding hole. The two transducers 153 of the acoustic driver 150may generate high-frequency sound of equal amplitude and opposite phasesunder the control of the controller, respectively. One of thetransducers may output normal-phase high-frequency sound, and transmitthe normal-phase high-frequency sound along a third acoustic route to asecond sound guiding hole. The other transducer may output reverse-phasehigh-frequency sound, and transmit the reverse-phase high-frequencysound along the fourth acoustic route to another second sound guidinghole.

In some embodiments, the transducer 143 and/or the transducer 153 may beof various suitable types. For example, the transducer 143 and thetransducer 153 may be dynamic coil speakers, which may have thecharacteristics of a high sensitivity in low-frequency, a large divedepth of low-frequency, and a small distortion. As another example, thetransducer 143 and the transducer 153 may be moving iron speakers, whichmay have the characteristics of a small size, a high sensitivity, and alarge high-frequency range. As another example, the transducers 143 and153 may be air-conducted speakers, or bone-conducted speakers. Asanother example, the transducer 143 and the transducer 153 may bebalanced armature speakers. In some embodiments, the transducer 143 andthe transducer 153 may be different types of transducers. For example,the transducer 143 may be a moving iron speaker, and the transducer 153may be a moving coil speaker. As another example, the transducer 1043may be a moving coil speaker, and the transducer 1053 may be a movingiron speaker.

In FIGS. 6A and 6B, the distance between the two point sound sources ofthe acoustic driver 140 may be d₁, and the distance between the twopoint sound sources of the acoustic driver 150 may be d₂, and d₁ may begreater than dz. As shown in FIG. 6B, the hearing position (that is, theposition of the ear canal when the user wears an acoustic output device)may be located on a line of a set of two point sound sources. In somealternative embodiments, the hearing position may be any suitableposition. For example, the hearing position may be located on a circlecentered on the center point of the two point sound sources. As anotherexample, the hearing position may be on the same side of two sets twopoint sound sources connection, or in the middle of a line connectingthe two sets two point sound sources.

It should be understood that the simplified structure of the acousticoutput device shown in FIGS. 6A and 6B may be merely by way of example,which may be not a limitation for the present disclosure. In someembodiments, the acoustic output device 400 and/or 500 may include asupporting structure, a controller, a signal processor, or the like, orany combination thereof.

FIG. 7A is a schematic diagram illustrating an acoustic output deviceaccording to some embodiments of the present disclosure. FIG. 7B is aschematic diagram illustrating another acoustic output device accordingto some embodiments of the present disclosure.

In some embodiments, acoustic drivers (e.g., acoustic drivers 140 or150) may include multiple groups of narrow-band speakers. As shown inFIG. 7A, the acoustic output device may include a plurality of groups ofnarrow-band speaker units and a signal processing unit. On the left orright side of the user, the acoustic output device may include n groups,respectively, with a total number of 2*n narrow-band speaker units. Eachgroup of narrow-band speaker units may have different frequency responsecurves, and the frequency response of each group may be complementaryand may collectively cover the audible sound frequency band. Thenarrow-band speaker herein may be an acoustic driver with a narrowerfrequency response range than the low-frequency acoustic driver andhigh-frequency acoustic driver. Taking the speaker unit located on theleft side of the user shown in FIG. 7A as an example: A1˜An and B1˜Bnform n groups of two point sound sources, respectively. When the sameelectrical signal is an input, each two point sound sources may generatesound with different frequency ranges. By setting the distance do ofeach two point sound sources, the near-field and far-field sound of eachfrequency band may be adjusted. For example, in order to enhance thevolume of near-field sound and reduce the volume of far-field leakage,the distance between the higher-frequency two point sound sources may beless than the distance of the lower-frequency two point sound sources.

In some embodiments, the signal processing unit may include an Equalizer(EQ) processing unit, and a Digital Signal Processor (DSP) processingunit. The signal processing unit may be used to implement signalequalization and other general digital signal processing algorithms(such as amplitude modulation and equal modulation). The processedsignal may output sound by being connected to a corresponding acousticdriver (e.g., a narrow-band speaker) structure. In some embodiments, thenarrow-band speaker may be a dynamic moving coil speaker or a movingiron speaker. In some embodiments, the narrow-band speaker may be abalanced armature speaker. Two point sound sources may be constructedusing two balanced armature speakers, and the sound output from the twospeakers may be in opposite phases.

In some embodiments, the acoustic drivers (such as acoustic drivers 140or 150) may include multiple groups of full-band speakers. As shown inFIG. 7B, the acoustic output device may include a plurality of sets offull-band speaker units and a signal processing unit. On the left orright side of the user, the acoustic output device may include n groups,respectively, with a total number of 2*n full-band speaker units. Eachfull-band speaker unit may have the same or similar frequency responsecurve, and may cover a wide frequency range.

Taking the speaker unit located on the left side of the user as shown inFIG. 7B as an example: A1˜An and B1˜Bn form n dual-point sound sources,respectively. The difference from FIG. 7A may be that the signalprocessing unit in FIG. 7B may include at least one set of filters forfrequency division of the sound source signal, and the electric signalscorresponding to different frequency ranges may be input into each groupof full-band speakers. In this way, each group of speaker units (similarto the dual-point sound sources) may produce sounds with differentfrequency ranges separately.

FIG. 8A is a schematic diagram illustrating an acoustic route accordingto some embodiments of the present disclosure. FIG. 8B is a schematicdiagram illustrating another acoustic route according to someembodiments of the present disclosure. FIG. 8C is a schematic diagramillustrating a further acoustic route according to some embodiments ofthe present disclosure.

As described above, a corresponding acoustic filtering network may beconstructed by setting structures such as a sound tube, a sound cavity,and a sound resistance in an acoustic route to achieve frequencydivision of sound. FIGS. 8A-8C show a schematic structural diagram offrequency division of a voice signal using an acoustic route. It shouldbe noted that FIGS. 8A-8C may be examples of setting the acoustic routewhen using the acoustic route to divide the voice signal, and may not bea limitation on the present disclosure.

As shown in FIG. 8A, an acoustic route may be composed of one or moregroups of lumen structures connected in series, and an acousticresistance material may be provided in the lumen to adjust the acousticimpedance of the entire structure to achieve a filtering effect. In someembodiments, a band-pass filtering or a low-pass filtering may beperformed on the sound by adjusting the size of the structures in thelumen and the acoustic resistance material to achieve frequency divisionof the sound. As shown in FIG. 8B, a structure with one or more sets ofresonant cavities (e.g., Helmholtz cavity) may be constructed on theacoustic route branch, and the filtering effect may be achieved byadjusting the size of each structure and the acoustic resistancematerial. As shown in FIG. 8C, a combination of a lumen and a resonantcavity (e.g., a Helmholtz cavity) structure may be constructed in anacoustic route, and a filtering effect may be achieved by adjusting thesize of each structure and the acoustic resistance material.

FIG. 9 is an exemplary graph illustrating sound leakage under a combinedaction of two sets of dual-point sound sources according to someembodiments of the present disclosure. FIG. 9 shows a curve of the soundleakage of an acoustic output device (e.g., the acoustic output device100, the acoustic output device 400, the acoustic output device 500, theacoustic output device 600, etc.) under the combined action of two setsof dual-point sound sources (e.g., a set of high-frequency dual-pointsound source and a set of low-frequency dual-point sound source). Thefrequency division points of the two sets of dual-point sound sourcesmay be around 700 Hz.

A normalization parameter α may be used to evaluate the volume of theleakage sound (for calculation of a, see Equation (4)). As shown in FIG.9, compared with the case of a single point sound source, the dual-pointsound source may have a relatively strong ability to reduce soundleakage. In addition, compared with the acoustic output device providedwith only one set of dual-point sound source, the two sets of dual-pointsound sources may output high-frequency sounds and low-frequency sounds,separately. A distance between the low-frequency dual-point sound sourcemay be greater than that of the high-frequency dual-point sound source.In the low-frequency range, by setting a larger distance (d₁) betweentwo point sound sources of a dual-point sound source, increment of thevolume of the near-field sound may be greater than increment of thevolume of the far-field leakage and may achieve a higher volume of thenear-field sound output in the low-frequency band. At the same time, inthe low-frequency range, the sound leakage of the dual-point soundsource may originally be relatively small. After the distance betweenthe two point sound sources is increased, the slightly increased soundleakage may still maintain a low level. In the high-frequency range, bysetting a relatively small distance (d2) between the two point soundsources of the dual-point sound source, the problems of the cutofffrequency of high-frequency sound leakage reduction being too low andthe audio band of the sound leakage reduction being too narrow may beovercome. By setting the distance d₁ between the two point sound sourcesof the dual-point sound source in the low-frequency band and thedistance d₂ between the two point sound sources of the dual-point soundsource in the high-frequency band, the acoustic output device providedin the embodiments of the present disclosure may obtain a stronger soundleakage suppressing capability than a single point sound source and aset of dual-point sound source.

In some embodiments, affected by factors such as the filtercharacteristics of the actual circuit, the frequency characteristics ofthe transducer, and the frequency characteristics of the acousticchannel, the actual low-frequency and high-frequency sounds of theacoustic output device may differ from those shown in FIG. 9. Inaddition, low-frequency and high-frequency sounds may have a certaincrossover (aliasing) in the frequency band near the frequency divisionpoint, causing the total sound leakage reduction of the acoustic outputdevice not to have a mutation at the frequency division point as shownin FIG. 9. Instead, there may be gradients and transitions in thefrequency band near the frequency division point, as shown in the thinsolid line in FIG. 9. It should be understood that these differences maynot affect the overall leakage reduction effect of the acoustic outputdevice provided by the embodiment of the present disclosure. Accordingto FIG. 4 to FIG. 9 and the related descriptions, the acoustic outputdevice provided by the present disclosure may be used to output soundsin different frequency bands by setting at least one high-frequencydual-point sound source and at least one low-frequency dual-point soundsource, so as to achieve a better sound output effect. In addition, bysetting different sets of dual-point sound sources with differentdistances, the acoustic output device may have a relatively strongercapability to reduce the sound leakage in a high frequency band and meetthe requirements of an open acoustic output device.

In another aspect of the present disclosure, another acoustic outputdevice may be provided. The acoustic output device may include at leastone set of acoustic drivers, and the sound generated by the at least oneset of acoustic drivers may propagate outwards through at least twoguiding holes acoustically coupled with the at least one set of acousticdrivers. In some embodiments, the acoustic output device may include abaffle, and the at least two guiding holes may be distributed on bothsides of the baffle, respectively. In some embodiments, the at least twoguiding holes may be distributed on both sides of the user's auricle. Inthis case, the auricle may serve as a baffle to separate the at leasttwo guiding holes, and the at least two guiding holes may have differentacoustic routes to the user's ear canal. More descriptions regarding thedual-point sound source and the baffle may be found in Internationalapplications No. PCT/CN2019/130921 and No. PCT/CN2019/130942, both filedon Dec. 31, 2019, the entire contents of each of which are herebyincorporated by reference.

FIG. 10 is a schematic diagram illustrating an exemplary acoustic outputdevice according to some embodiments of the present disclosure. As shownin FIG. 10, an acoustic output device 1000 may include a supportingstructure 1010 and an acoustic driver 1020, which may be disposed in thesupporting structure 1010. In some embodiments, the acoustic outputdevice 1000 may be worn on a user's body (e.g., the head, the neck, theupper torso, etc. of the user) e.g., through the supporting structure1010. The supporting structure 1010 and the acoustic driver 1020 may beclose to and not block an ear canal of the user. The ear of the user maybe in an open state. The user may hear a sound output from the acousticoutput device 1000 and a sound from an external source. For example, theacoustic output device 1000 may be arranged around or partially aroundthe user's ear and may transmit the sound via an air conduction manneror a bone conduction manner.

The supporting structure 1010 may be configured to support one or moreacoustic drivers 1020. In some embodiments, the supporting structure1010 may include an enclosed shell structure with an internal hollow,and the one or more acoustic drivers 1020 may be disposed in thesupporting structure 1010. In some embodiments, the acoustic outputdevice 1000 may be combined with a product such as a pair of glasses, aheadset, a display device, an AR/VR helmet, etc. In this case, thesupporting structure 1010 may be fixed near the user's ear via a hangingmanner or a clamping manner. In some embodiments, the supportingstructure 1010 may include a hook, a shape of the hook may be matchedthe shape of the auricle, and the acoustic output device 1000 may beworn on the user's ear through the hook, independently. The acousticoutput device 1000, which is worn on the user's ear independently may becommunicated with a signal source (e.g., a computer, a mobile phone, orother mobile devices) in a wired or wireless manner (e.g., Bluetooth).For example, the acoustic output device 1000 worn on the left ear and/orthat worn on the right ear may be directly communicated with the signalsource via a wireless manner. As another example, the acoustic outputdevice 1000 worn at the left and/or right ear may include a first outputpart and a second output part. The first output part may be communicatedwith the signal source, and the second output part may be connected tothe first output part via a wireless manner. The sound may be outputsynchronously by the first output part and the second output partcontrolled by one or more synchronization signals. The wireless mannermay include but not limited to Bluetooth, a local area network, a widearea network, a wireless personal area network, a near-fieldcommunication, or the like, or any combination thereof.

In some embodiments, the supporting structure 1010 may include a shellstructure, and a shape of the supporting structure 1010 may be matched ashape of the ear of the user. The shape of the supporting structure 1010may include a circular ring, an oval, a (regular or irregular)polygonal, a U-shape, a V-shape, a semi-circle, etc., and the supportingstructure 1010 may be directly anchored at the user's ear. In someembodiments, the supporting structure 1010 may also include one or morefixed parts. The fixed part may include an ear hook, a head beam, anelastic band, or the like, or any combination thereof, which may be usedto fix the acoustic output device 1000 on the user and prevent theacoustic output device 1000 from falling. Merely by way of example, theelastic band may include a headband that may be worn around the head ofthe user. As another example, the elastic band may include a neckbandwhich may be worn around the neck/shoulder of the user. In someembodiments, the elastic band may include a continuous band and beelastically stretched to be worn on the head of the user. In this case,the elastic band may also add pressure on the head of the user, therebycausing the acoustic output device 1000 to be fixed to a certainposition of the head. In some embodiments, the elastic band may includea discontinuous band. For example, the elastic band may include a rigidportion and a flexible portion. The rigid portion may be made of rigidmaterial (e.g., a plastic, a metal, etc.), and the rigid portion may befixed to the supporting structure 1010 of the acoustic output device1000 via a physical connection (e.g., a snap connection, a screwconnection, etc.). The flexible portion may be made of an elasticmaterial (e.g., a cloth, a composite material, a neoprene, etc.).

In some embodiments, when the user wears the acoustic output device1000, the supporting structure 1010 may be placed above or below theauricle. The supporting structure 1010 may also include a sound guidinghole 1011 and a sound guiding hole 1012, which may be configured totransmit sounds. In some embodiments, the sound guiding hole 1011 andthe sound guiding hole 1012 may be placed on two sides of the user'sauricle, respectively. The acoustic driver 1020 may output sound(s)through the sound guiding hole 1011 and/or the sound guiding hole 1012.

The acoustic driver 1020 may be configured to receive an electricalsignal, and convert the electrical signal into a voice signal which maybe output. In some embodiments, a type of the acoustic driver 1020 mayinclude an acoustic driver with a low-frequency, an acoustic driver witha high-frequency, an acoustic driver with a full-frequency, or the like,or any combination thereof, according to the frequency of the acousticdriver 1020. In some embodiments, the acoustic driver 120 may include amoving coil acoustic driver, a moving iron acoustic driver, apiezoelectric acoustic driver, an electrostatic acoustic driver, amagnetostrictive acoustic driver according to a principle of theacoustic driver 1020.

In some embodiments, the acoustic driver 1020 may include a vibrationdiaphragm. When the vibration diaphragm vibrates, sounds may betransmitted from a front side and a rear side of the vibrationdiaphragm, respectively. In some embodiments, a front chamber 1013 maybe disposed on the front side of the vibration diaphragm in thesupporting structure 1010, which may be configured to transmit thesound(s). The front chamber 1013 may be acoustically coupled with thesound guiding hole 1011. The sound transmitted from the front side ofthe vibration diaphragm may be transmitted from the sound guiding hole1011 through the front chamber 1013. A rear chamber 1014 may be disposedon the rear side of the vibration diaphragm in the supporting structure1010, which may be configured to transmit the sound(s). The rear chamber1014 may be acoustically coupled with the sound guiding hole 1012. Thesound transmitted from the rear side of the vibration diaphragm may betransmitted from the sound guiding hole 1012 through the rear chamber1014. It should be noted that, when the vibration diaphragm vibrates,the front side and the rear side of the vibration diaphragm maysimultaneously generate sounds with opposite phases. After passingthrough the front chamber 1013 and rear chamber 1014, respectively, thesounds may be transmitted outward from the sound guiding hole 1011 andthe sound guiding hole 1012. In some embodiments, the sounds output bythe acoustic driver 1020, which may be transmitted through the soundguiding hole 1011 and the sound guiding hole 1012 may meet the specificrequirement by setting a structure of at least one of the front chamber1013 and the rear chamber 1014. For example, the sound guiding hole 1011and the sound guiding hole 1012 may transmit a set of sounds with aspecific phase relationship (e.g., opposite phases) by designing alength of at least one of the front chamber 1013 and the rear chamber1014, thereby increasing a volume in the near-field of the acousticoutput device 1000, avoiding sound leakage of the acoustic output device1000, and effectively improving the performance of the acoustic outputdevice 1000. As used herein, a length of a front chamber refers to alength of a route between the vibration diaphragm to a guiding holecoupled with the front chamber when a sound (i.e., vibration) propagatesfrom the vibration diaphragm to the guiding hole along the route, and alength of a rear chamber refers to a length of a route between thevibration diaphragm to a guiding hole coupled with the rear chamber whena sound (i.e., vibration) propagates from the vibration diaphragm to theguiding hole along the route.

In some alternative embodiments, the acoustic driver 1020 may include aplurality of vibration diaphragms (e.g., two vibration diaphragms). Theplurality of vibration diaphragms may vibrate to generate sounds,respectively. Each of the sounds may be transmitted pass through achamber that is connected to one of the vibration diaphragms in thesupporting structure and may be output from a corresponding soundguiding hole. The plurality of vibration diaphragms may be controlled bythe same controller or different controllers. The plurality of vibrationdiaphragms may generate sounds that satisfy a requirement of certainphase(s) and/or amplitude(s) (e.g., sounds with the same amplitude andopposite phases, sounds with different amplitudes and opposite phases,etc.).

As mentioned above (e.g., FIG. 3A, 3B and the related descriptionsthereof), when a sound frequency is constant, as the distance betweentwo point sound sources of the dual-point sound source increases, thevolume of the hearing sound and the volume of the leakage soundcorresponding to the dual-point sound source may increase. For a clearerdescription, the relationship between the volume of the hearing sound,the volume of the leakage sound, and the distance d of the two pointsound sources may be further explained according to FIG. 11 to FIG. 13.

FIG. 11 is a schematic diagram illustrating two point sound sources anda hearing position according to some embodiments of the presentdisclosure. As shown in FIG. 11, a point sound source a₁ and a pointsound source a₂ may be disposed on the same side of the hearingposition, and the point sound source a₁ may be closer to the hearingposition. The point sound source a₁ and the point sound source a₂ mayoutput sounds with the same amplitude and opposite phases.

FIG. 12 is a graph illustrating a change of a volume of a hearing soundof a dual-point sound source with different distances along with afrequency according to some embodiments of the present disclosure. Theabscissa represents the frequency (f) of the sound output by thedual-point sound source, and the unit may be hertz (Hz). The ordinaterepresents the volume of the sound, and the unit may be decibel (dB). Asshown in FIG. 12, as the distance between the point sound source a₁ andthe point sound source a₂ gradually increases (e.g., from d to 10 d),the sound volume at the hearing position may be gradually increased. Asthe distance between the point sound source a₁ and the point soundsource a₂ increases, a difference between sound pressure amplitudes(i.e., sound pressure difference) of the two sounds reaching the hearingposition may be increased, and a difference of acoustic routes may beincreased, thereby reducing the sound cancellation and increasing thesound volume at the hearing position. Due to the existence of the soundcancellation, the sound volume at the hearing position may be less thanthat generated by a single-point sound source with the same intensity asthe two-point sound sources in a middle-low-frequency (e.g., less than1000 Hz). For a high-frequency (e.g., close to 10000 Hz), a wavelengthof the sound may be decreased, a condition for enhancing the sound maybe formed, and the sound volume at the hearing position generated by thetwo-point sound sources may be greater than a sound volume at thehearing position generated by the single-point sound source. As usedherein, the sound pressure amplitude (i.e., a sound pressure) refers toa pressure generated by the sound through the vibration of the air.

In some embodiments, the sound volume at the hearing position may beincreased by increasing the distance between the point sound sources(e.g., the point sound source a₁ and the point sound source a₂) of thedual-point sound source. As the distance increases, the soundcancellation of the dual-point sound source may be weakened, therebyincreasing sound leakage in the far-field. For illustration purposes,FIG. 13 is a graph illustrating a change of a normalized parameter of adual-point sound source in a far-field along with a frequency accordingto some embodiments of the present disclosure. The abscissa mayrepresent the frequency (f) of the sound, the unit may be Hertz (Hz),the ordinate may use a normalized parameter α for evaluating the volumeof the leakage sound, and the unit may be decibel (dB). As shown in FIG.13, taking the far-field normalized parameter α of a single point soundsource as a reference, as the distance between two point sound sourcesof the dual-point sound source increases from d to 10 d, the far-fieldnormalized parameter α may gradually increase, indicating the soundleakage may gradually increase. More descriptions regarding thenormalized parameter α may be found in Equation (4) and relateddescriptions.

In some embodiments, adding a baffle to the acoustic output device maybe beneficial to improve the output effect of the acoustic outputdevice, for example, increase the sound intensity of the hearingposition in the near-field and reduce the sound leakage in thefar-field. For illustration purposes, FIG. 14 is a schematic diagramillustrating an exemplary baffle disposed between two point soundsources of a dual-point sound source according to some embodiments ofthe present disclosure. As shown in FIG. 14, when the baffle is disposedbetween a point sound source a₁ and a point sound source a₂, a soundfield of the point sound source a₂ may bypass the baffle to interferewith a sound wave of the point sound source a₁ at a hearing position inthe near-field, which may increase a length of an acoustic route betweenthe point sound source a₂ and the hearing position. Assuming that thepoint sound source a₁ and the point sound source a₂ have the sameamplitude, an amplitude difference between the sound waves of the pointsound source a₁ and that of the point sound source a₂ at the hearingposition may be greater than that in a case without a baffle, therebyreducing a sound cancellation of the two sounds at the hearing position,increasing a sound volume at the hearing position. In the far-field, thesound waves generated by the point sound source a₁ and the point soundsource a₂ may not bypass the baffle in a relatively large space, thesound waves may be interfered (as a case without the baffle). Comparedto the case without the baffle, the sound leakage in the far-field maybe not increased significantly. Therefore, the baffle being disposedbetween the point sound source a₁ and the point sound source a₂ maysignificantly increase the sound volume at the hearing position in thenear-field and not significantly increase that of the leakage sound inthe far-field.

In the present disclosure, when the two point sound sources of thedual-point sound source are arranged on both sides of the auricle, theauricle may serve as a baffle, thus the auricle may also be referred toas a baffle for convenience. Merely by way of example, due to theexistence of the auricle, a sound in the near-field may be generated bythe dual-point sound source with a distance D1 (also referred to as Mode1). A sound in the far-field may be generated by the dual-point soundsource with a distance D2 (also referred to as Mode 2), and D1>D2. FIG.15 is a graph illustrating a change of a volume of a hearing sound alongwith a frequency when a user's auricle is arranged between two pointsound sources of a dual-point sound source according to some embodimentsof the present disclosure. As shown in FIG. 15, for a low-frequency(e.g., a frequency less than 1000 Hz), a volume of the sound in thenear-field (i.e., a sound heard by an ear of a user) may be the same asor similar to that in Mode 1 when the dual-point sound source arelocated on two sides of the auricle, which may be greater than a volumeof a sound in the near-field in Mode 2 and may be close to a volume of asound in a near-field of a single-point sound source. As the frequencyincreases (e.g., 2000 Hz˜7000 Hz), the volume of the sound in thenear-field in Mode 1 and generated by the two point sound sources of thedual-point sound source located on two sides of the auricle may begreater than that of the single-point sound source. It should beunderstood that, when the auricle is located between the two point soundsources of the dual-point sound source, the volume of the sound in thenear-field transmitted from a sound source to the ear may be effectivelyincreased. FIG. 16 is a graph illustrating a change of a volume of aleakage sound along with a frequency when an auricle is arranged betweentwo point sound sources of a dual-point sound source according to someembodiments of the present disclosure. As shown in FIG. 16, as thefrequency increases, the sound leakage in the far-field may beincreased. When the dual-point sound source is located on two sides ofthe auricle, the sound leakage in the far-field leakage generated by thedual-point sound source may be the same as (or substantially same as)the sound leakage in the far-field in Mode 2, which may be less than thesound leakage in far-field in Mode 1 and/or the sound leakage in thefar-field leakage generated by a single-point sound source. Therefore,when the auricle is located between the two point sound sources of thedual-point sound source, the sound transmitted from the sound source tothe far-field may be effectively reduced, that is, the sound leakagefrom the sound source to the surroundings may be effectively reduced.FIG. 17 is a graph illustrating a change of a normalized parameter alongwith a frequency when two point sound sources of a dual-point soundsource of an acoustic output device are disposed on two sides of anauricle according to some embodiments of the present disclosure. Asshown in FIG. 17, when the frequency is less than 10000 Hz, thenormalized parameter when two point sound sources of the dual-pointsound source are distributed on both sides of the auricle may be lessthan the normalized parameter in the Mode 1 (in which there is no thebaffle disposed between the two point sound sources of the dual-pointsound source, and a distance between the two point sound sources is D₁),a Mode 2 (in which there is no baffle disposed between the two pointsound sources of the dual-point sound source, and the distance betweenthe two point sound sources is D₂), or a single point sound source,which may indicate that when the two point sound sources of thedual-point sound source are disposed on the two sides of the auricle,the acoustic output device may have a better capability to reduce thesound leakage. In order to further explain an effect on the acousticoutput of the acoustic output device 100 with or without a bafflebetween two point sound sources of a dual-point sound source or twosound guiding holes, a volume of a sound at the hearing position in anear-field and/or a volume of sound leakage in a far-field leakage underdifferent conditions may be described below.

FIG. 18 is a graph illustrating a change of a volume of hearing soundand a volume of leakage sound along with a frequency with and without abaffle between two point sound sources of a dual-point sound sourceaccording to some embodiments of the present disclosure. As shown inFIG. 18, when the baffle is disposed between the two point sound sourcesof the dual-point sound source (i.e., two sound guiding holes) of theacoustic output device, a distance between the two point sound sourcesof the dual-point sound source may be increased in the near-field, andthe volume of the sound at the hearing position in the near-field may beequivalent to being generated by dual-point sound source with arelatively large distance, thereby increasing the volume of the sound inthe near-field compared to a case without the baffle. In the far-field,the interference of sound waves generated by the dual-point sound sourcemay be not significantly affected by the baffle, the sound leakage maybe regarded as being generated by a set of dual-point sound source witha relatively small distance, and the sound leakage may be not changedsignificantly with or without the baffle. The baffle disposed betweenthe two sound guiding holes (the dual-point sound source) may improvethe performance of the acoustic output device by reducing the soundleakage, and increase the volume of the sound in the near-field, therebyreducing requirements for a component that plays an acoustic role in theacoustic output device, reducing the electrical loss of the acousticoutput device, and prolonging a working time of the acoustic outputdevice.

FIG. 19 is a graph illustrating changes of a volume of a hearing soundand a volume of a leakage sound along with a distance between two pointsound sources of a dual-point sound source at a frequency of 300 Hz andwith or without a baffle according to some embodiments of the presentdisclosure. FIG. 20 is a graph illustrating changes of a volume of ahearing sound and a volume of a leakage sound along with a distancebetween two point sound sources of a dual-point sound source at afrequency of 1000 Hz and with or without a baffle according to someembodiments of the present disclosure. As shown in FIG. 19 and FIG. 20,in the near-field, when the frequency is 300 Hz or 1000 Hz, a volume ofa heard sound when a baffle is disposed between the two point soundsources of the dual-point sound source is greater than a volume of aheard sound when the baffle is not disposed between the two point soundsources of the dual-point sound source as the distance d of thedual-point sound source is increased. In this case, the baffle disposedbetween the two point sound sources of the dual-point sound source mayeffectively increase the volume of the heard sound in the near-fieldwhen the frequency is 300 Hz or 1000 Hz. In a far-field, a volume of aleakage sound when the baffle is disposed between the two point soundsources of the dual-point sound source may be equivalent to (orsubstantially equivalent to) a volume of the leakage sound when thebaffle is not disposed between the two point sound sources of thedual-point sound source, which may show that the baffle disposed betweenthe two point sound sources of the dual-point sound source may notaffect on the sound leakage in the far-field when the frequency is 300Hz or 1000 Hz.

FIG. 21 is a graph illustrating changes of a volume of a hearing soundand a volume of a leakage sound along with a distance between two pointsound sources of a dual-point sound source at a frequency of 5000 Hz andwith or without a baffle according to some embodiments of the presentdisclosure. As shown in FIG. 21, in the near-field, when the frequencyis 5000 Hz, a volume of a heard sound when a baffle is disposed betweenthe two point sound sources of the dual-point sound source is greaterthan a volume of a heard sound when the baffle is disposed between thetwo point sound sources of the dual-point sound source as the distance dof the dual-point sound source is increased. In the far-field, a volumeof a leakage sound of the dual-point sound source may be fluctuant as afunction of the distance d when the baffle is disposed and not disposedbetween the two point sound sources of the dual-point sound source.Overall, whether the baffle is disposed between the two point soundsources of the dual-point sound source may have little effect on thesound leakage in the far-field.

FIG. 22 is a graph illustrating a change of a volume of hearing soundalong with a frequency when a distance d between two point sound sourcesof a dual-point sound source is 1 cm according to some embodiments ofthe present disclosure. FIG. 23 is a graph illustrating a change of avolume of a hearing sound along with a frequency when a distance dbetween two point sound sources dual-point sound source is 2 cmaccording to some embodiments of the present disclosure. FIG. 24 is agraph illustrating a change of a volume of hearing sound along with afrequency when a distance d between two point sound sources of adual-point sound source is 4 cm according to some embodiments of thepresent disclosure. FIG. 25 is a graph illustrating a change of anormalized parameter along with a frequency when a distance d betweentwo point sound sources of a dual-point sound source is 1 cm accordingto some embodiments of the present disclosure. FIG. 26 is a graphillustrating a change of a normalized parameter along with a frequencywhen a distance d between two point sound sources of a dual-point soundsource is 2 cm according to some embodiments of the present disclosure.FIG. 27 is a graph illustrating a change of a normalized parameter alongwith a frequency when a distance d between two point sound sources of adual-point sound source is 4 cm according to some embodiments of thepresent disclosure. As shown in FIG. 22 to FIG. 24, for differentdistance d (e.g., 1 cm, 2 cm, 4 cm) between sound guiding holes, at acertain frequency, in a hearing position in the near-field (e.g., an earof a user), a volume of a sound generated by two sound guiding holeswhich may be disposed on two sides of the auricle (i.e., in the case of“without baffle” shown in FIGS. 22-24) may be greater than a volume of asound generated by two sound guiding holes which may be not disposed onthe two sides of the auricle. The certain frequency may be below 10000Hz, 5000 Hz, or 1000 Hz.

As shown in FIGS. 25 to 27, for different distances d (e.g., 1 cm, 2 cm,4 cm, etc.) between sound guiding holes, at a certain frequency, infar-field (e.g., a position away from an ear of a user), a volume of aleakage sound generated by the two sound guiding holes which may bedisposed on two sides of an auricle, may be smaller than that generatedby the two sound guiding holes which may be not disposed on two sides ofthe auricle. It should be noted that as the distance between the twosound guiding holes or two-point sound sources increases, theinterference cancellation of a sound at a position in the far-field maybe weakened, the sound leakage in the far-field may be increased, andthe ability for reducing the sound leakage may be reduced. The distanced between the two sound guiding holes or the two-point sound sources maybe not greater than a distance threshold. In some embodiments, thedistance d between the two sound guiding holes may be set to be lessthan 20 cm, 12 cm, 10 cm, 6 cm, etc. to increase the volume in thenear-field and reduce the sound leakage in the far-field. In someembodiments, considering a size of the acoustic output device and astructural requirement for the sound guiding hole(s), the distance dbetween the two sound guiding holes may be set to be no less than 1 cmand no greater than 12 cm, no less than 1 cm and no more than 10 cm, noless than 1 cm and no more than 8 cm, no less than 1 cm and no more than6 cm, no less than 1 cm and no more than 3 cm, etc.

It should be noted that the above description is merely for theconvenience of description, and not intended to limit the scope of thepresent disclosure. It should be understood that, for those skilled inthe art, after understanding the principle of the present disclosure,various modifications and changes in the forms and details of theacoustic output device may be made without departing from thisprinciple. For example, in some embodiments, a plurality of soundguiding holes may be set on two sides of the baffle. The count of theplurality of sound guiding holes disposed on each of the two sides ofthe baffle may be the same or different. For example, the count of soundguiding holes disposed on one side of the baffle may be two, and thecount of sound guiding holes disposed on the other side may be two orthree. These modifications and changes may still be within theprotection scope of the present disclosure.

In some embodiments, for a certain distance between the two point soundsources of the dual-point sound source, a relative position of thehearing position to the dual-point sound source may affect the volume ofthe sound in the near-field and the sound leakage in the far-field. Toimprove the acoustic output performance of the acoustic output device,in some embodiments, the acoustic output device may include at least twosound guiding holes. The at least two sound guiding holes may includetwo sound guiding holes which may be disposed on a front side and/or arear side of the auricle of a user, respectively. In some embodiments, asound propagated from the sound guiding hole disposed on the rear sideof the auricle may bypass the auricle to an ear canal of the user, andan acoustic route between the sound guiding hole disposed on the frontside of the auricle and the ear canal (i.e., the acoustic distance fromthe sound guiding hole to an ear canal entrance) may be shorter than anacoustic route between the sound guiding hole disposed on the rear sideof the auricle and the ear. FIG. 28 is a schematic diagram illustratinghearing positions according to some embodiments of the presentdisclosure. In order to further explain an effect of the hearingposition on the acoustic output, four hearing positions (i.e., a hearingposition 1, a hearing position 2, a hearing position 3, and a hearingposition 4) may be selected as shown in FIG. 28, which may be used todescribe the effect and criteria of the hearing positions. A distancebetween each of the hearing position 1, the hearing position 2, and thehearing position 3 and a point sound source a₁ may be equal, which maybe denoted by r₁. A distance between the hearing position 4 and thepoint sound source a₁ may be denoted by r₂, and r₂<r₁. The point soundsource a₁ and a point sound source a₂ may generate sounds with oppositephases.

FIG. 29 is a graph illustrating a volume of hearing sound generated by adual-point sound source without baffle at different hearing positions ina near field along with a frequency according to some embodiments of thepresent disclosure. FIG. 30 is a graph illustrating a normalizedparameter at different hearing positions obtained with reference toEquation (4) on the basis of FIG. 29 along with a frequency. As shown inFIGS. 29 and 30, an acoustic route difference between an acoustic routefrom the point sound source a₁ to the hearing position 1 and an acousticroute from the point sound source a₂ to the hearing position 1 isrelatively small, and accordingly an interference of sounds generated bythe dual-point sound source at the hearing position 1 may decrease thevolume of a heard sound at the hearing position 1 to be relativelysmaller than that of other hearing positions. For a hearing position 2,compared with the hearing position 1, a distance between the hearingposition 2 and the point sound source a₁ may be the same as that betweenthe hearing position 1 and the point sound source a₁, that is, anacoustic route from the point sound source a₁ to the hearing position 2may be the same as that from the point sound source a₁ to the hearingposition. A distance between the hearing position 2 and the point soundsource a₂ may be longer than that between the hearing position 1 and thepoint sound source a₂, and an acoustic route from the point sound sourcea₂ to the hearing position 2 may be greater than that from the pointsound source a₂ to the hearing position 1. An amplitude differencebetween the sound generated by the point sound source a₁ and the soundgenerated by the point sound source a₂ may be increased at the hearingposition 2. Accordingly, a volume of the sound transmitted from thedual-point sound source after being interfered at the hearing position 2may be greater than that at the hearing position 1. Among a plurality ofpositions on an arc with a radius of r₁, a difference between theacoustic route from the point sound source a₁ to the hearing position 3and the acoustic route from the point sound source a₂ to the hearingposition 3 may be the longer than other acoustic routes. Compared withthe hearing position 1 and the hearing position 2, a volume of a heardsound at the hearing position 3 may be higher than that at other hearingpositions. For the hearing position 4, a distance between the hearingposition 4 and the point sound source a₁ may be relatively short, asound amplitude of a sound generated by the point sound source a₁ at thehearing position 4 may be greater than the sound amplitude of the soundgenerated by the point sound source a₁ at other hearing positions, and avolume of a heard sound at the hearing position 4 may be greater thanother volumes of heard sounds at other hearing positions. In closing,the volume of the heard sound at the hearing position in the near-fieldmay be changed when the hearing position and/or a relative position ofthe dual-point sound source is changed. When the hearing position (e.g.,hearing position 3) is on the line between the two point sound sourcesof the dual-point sound source and on the same side of the dual-pointsound source, the acoustic route difference between the two point soundsources of the dual-point sound source at the hearing position may bethe largest (the acoustic route difference may be the distance d betweenthe two point sound sources of the dual-point sound source). In thiscase (i.e., when the auricle is not used as a baffle), the volume of theheard sound at the hearing position may be greater than that at otherpositions. According to Equation (4), the sound leakage in the far-fieldis constant, the normalized parameter corresponding to the hearingposition may be relatively small, and a capability for reducing thesound leakage may be relatively strong. Further, the distance r₁ betweenthe hearing position (e.g., the hearing position 4) and the point soundsource A₁ may be decreased, thereby increasing the volume of the heardsound at the hearing position, reducing the sound leakage parameter, andimproving the capability of reducing sound leakage.

FIG. 31 is a graph illustrating a volume of a hearing sound at differenthearing positions in a near field of a dual-point sound source (shown inFIG. 28) with a baffle along with a frequency according to someembodiments of the present disclosure. FIG. 32 is a graph illustrating anormalized parameter at different hearing positions obtained withreference to Equation (4) on the basis of FIG. 31 along with afrequency. As shown in FIGS. 31 and 32, compared to a case without abaffle, a volume of a heard sound generated by the dual-point soundsource at the hearing position 1 may be increased when the baffle isdisposed between the two point sound sources of the dual-point soundsource. The volume of the heard sound at the hearing position 1 may begreater than that at the hearing position 2 and/or the hearing position3. An acoustic route from the point sound source a₂ to the hearingposition 1 may be increased when the baffle is disposed between the twopoint sound sources of the dual-point sound source, and accordingly, anacoustic route difference between the two point sound sources of thedual-point sound source and the hearing position 1 may be increased. Anamplitude difference between the sounds generated by the dual-pointsound source at the hearing position 1 may be increased, and the soundinterference cancellation may be not formed, thereby increasing thevolume of the heard sound generated at the hearing position 1. At thehearing position 4, a distance between the hearing position 4 and thepoint sound source a₁ may be decreased, the sound amplitude of the pointsound source a₁ at the hearing position may be relatively great. Thevolume of the heard sound at the hearing position 4 may be greater thanthat at other hearing positions (i.e., the hearing position 1, thehearing position 2, and/or the hearing position 3). For the hearingposition 2 and the hearing position 3, an effect of the baffle on theacoustic route from the point sound source a₂ to the hearing positionsmay be not obvious, the increase of the volume of the heard sound at thehearing position 2 and the hearing position 3 may be less than that atthe hearing position 1 and the hearing position 4 which are locatedclose to the baffle.

The volume of leakage sound in the far-field may be not changed, and thevolume of the heard sound at the hearing position in the near-field maybe changed when the hearing position is changed. In this case, accordingto Equation (4), the normalized parameter of the acoustic output devicemay be different at different hearing positions. Specifically, a hearingposition with a relatively large volume of the heard sound (e.g., thehearing position 1 and/or the hearing position 4) may correspond to asmall normalized parameter and a strong capability for reducing thesound leakage. A hearing position with a low volume of the heard sound(e.g., the hearing position 2 and hearing position 3) may correspond toa large normalized parameter and a weak capability for reducing thesound leakage.

According to an actual application scenario of the acoustic outputdevice, an auricle of a user may be served as the baffle. In this case,the two sound guiding holes on the acoustic output device may bearranged on a front side and a rear side of the auricle, respectively,and an ear canal may be located between the two sound guiding holes as ahearing position. In some embodiments, a distance between the soundguiding hole on the front side of the auricle and the ear canal may besmaller than a distance between the sound guiding hole on the rear sideof the auricle and the ear canal by adjusting positions of the two soundguiding holes on the acoustic output device. In this case, the acousticoutput device may produce a relatively large sound amplitude at the earcanal since the sound guiding hole on the front side of the auricle isclose to the ear canal. The sound amplitude formed by the sound guidinghole on the rear side of the auricle may be smaller at the ear canal,which may avoid the interference cancellation of the sounds from the twosound guiding holes at the ear canal, thereby ensuring a relativelylarge volume of the heard sound at the ear canal. In some embodiments,the acoustic output device may include one or more contact points (e.g.,“an inflection point” on a supporting structure to match a shape of theear) which may contact with the auricle when the acoustic output deviceis worn. The contact point(s) may be located on a line connecting thetwo sound guiding holes or on one side of the line connecting the twosound guiding holes. And a ratio of a distance between the sound guidinghole disposed on the front side of the auricle and the contact point(s)and a distance between the sound guiding hole disposed on the rear sideof the auricle and the contact point(s) may be 0.05-20, 0.1-10, 0.2-5,0.4-2.5, etc.

FIG. 33 is a diagram illustrating a dual-point sound source and a baffle(e.g., an auricle) according to some embodiments of the presentdisclosure. In some embodiments, a position of the baffle disposedbetween the two sound guiding holes may affect the acoustic output of anacoustic output device. Merely by way of example, as shown in FIG. 33,the baffle may be disposed between a point sound source a₁ and a pointsound source a₂, a hearing position may be located on a line connectingthe point sound source a₁ and the point sound source a₂. In addition,the hearing position may be located between the point sound source a₁and the baffle. A distance between the point sound source a₁ and thebaffle may be L. A distance between the point sound source a₁ and thepoint sound source a₂ may be d. A distance between the point soundsource a₁ and the heard sound may be L₁. A distance between the hearingposition and the baffle may be L₂. When the distance L₁ is constant, amovement of the baffle may change a ratio of L to d, and a volume of theheard sound at the hearing position and/or a volume of a sound leakagein a far-field may be obtained.

FIG. 34 is a graph illustrating a change of a volume of a sound in anear-field along with a frequency when a baffle is at differentpositions according to some embodiments of the present disclosure. FIG.35 is a graph illustrating a change of a volume of a leakage sound in afar-field along with a frequency when a baffle is at different positionsaccording to some embodiments of the present disclosure. FIG. 36 is agraph illustrating a change of a normalized parameter along with afrequency when a baffle is at different positions according to someembodiments of the present disclosure. As shown in FIGS. 34-36, thesound leakage in the far-field may be not changed or a change of thesound leakage in the far-field may be less than a sound threshold whenthe position of the baffle is changed between the two point soundsources of the dual-point sound source. When a distance d between thepoint sound source a₁ and the point sound source a₂ is constant, when Lis decreased, a volume of a sound at a hearing position may beincreased, the normalized parameter may be decreased, and the capabilityfor reducing sound leakage may be enhanced. When L increases, the volumeat the hearing position may be increased, the normalized parameter maybe increased, and the capability for reducing the sound leakage may beweakened. When L is relatively small, the hearing position may be closeto the baffle, an acoustic route of a sound wave from the point soundsource a₂ to the hearing position may be increased in the existence ofthe baffle. In this case, an acoustic route difference between anacoustic route from the point sound source a₁ to the hearing positionand an acoustic route from the point sound source a₂ to the hearingposition may be increased and the interference cancellation of the soundmay be reduced. The volume of the sound at the hearing position may beincreased in the existence of the baffle. When L is relatively large,the hearing position may be far away from the baffle. The baffle may notaffect (or barely affect) the acoustic route difference. The volume atthe hearing position may be not changed when the baffle is added.

As described above, by adjusting positions of the sound guiding holes onthe acoustic output device, the auricle of the user may be served as thebaffle to separate sound guiding holes when the user wears the acousticoutput device. In this case, the structure of the acoustic output devicemay be simplified, and the output effect of the acoustic output devicemay be further improved. In some embodiments, the positions of the twosound guiding holes may be determined so that a ratio of a distancebetween the sound guiding hole on the front side of the auricle and theauricle (or a contact point on the acoustic output device for contactwith the auricle) to a distance between the two sound guiding holes maybe less than or equal to 0.5, 0.3, 0.1, etc. when the user wears theacoustic output device. In some embodiments, the ratio of the distancebetween the sound guiding hole on the front side of the auricle and theauricle to the distance between the two sound guiding holes may belarger than or equal to 0.05. In some embodiments, a ratio of thedistance between the two sound guiding holes to a height of the auriclemay be greater than or equal to 0.2. In some embodiments, the ratio maybe less than or equal to 4. In some embodiments, the height of theauricle may refer to a length of the auricle in a directionperpendicular to a sagittal plane.

It should be noted that an acoustic route from an acoustic driver to asound guiding hole in the acoustic output device may affect the volumeof the sound in the near-field and sound leakage in the far-field. Theacoustic route may be changed by adjusting a length of a chamber betweena vibration diaphragm in the acoustic output device and the soundguiding hole. In some embodiments, the acoustic driver may include thevibration diaphragm. A front side and a rear side of the vibrationdiaphragm may be coupled to two sound guiding holes through a frontchamber and a rear chamber, respectively. The acoustic route from thevibration diaphragm to each of the two sound guiding holes may bedifferent. In some embodiments, a ratio of the acoustic route from thevibration diaphragm to one of the two sound guiding holes to theacoustic route from the vibration diaphragm to another of the two soundguiding holes may be 0.5-2, 0.6-1.5, 0.8-1.2, etc.

In some embodiments, when the two sound guiding holes transmit thesounds with opposite phases, amplitudes of the sounds may be adjusted toimprove the output performance of the acoustic output device.Specifically, the amplitude of the sound transmitted by each of the twosound guiding holes may be adjusted by adjusting an impedance of anacoustic route between the sound guiding hole and an acoustic driver. Insome embodiments, the impedance may refer to a resistance that anacoustic wave overcomes when the acoustic wave is transmitted in amedium. In some embodiments, the acoustic route may be or may not befilled with damping material (e.g., a tuning net, tuning cotton, etc.)to adjust the sound amplitude. For example, a resonance cavity, a soundhole, a sound slit, a tuning net, a tuning cotton, or the like, or anycombination thereof, may be disposed in the acoustic route to adjust theacoustic resistance, thereby changing the impedance of the acousticroute. As another example, a hole size of each of the two sound guidingholes may be adjusted to change the acoustic resistance of the acousticroute. In some embodiments, a ratio of acoustic impedance between theacoustic driver (e.g., the vibration diaphragm of the acoustic driver)and the two sound guiding holes may be 0.5-2, 0.8-1.2, etc.

It should be noted that the above descriptions are merely forillustration purposes, and not intended to limit the present disclosure.For example, the hearing position may not be on the line connecting thedual-point sound source, but may also be above, below, or in anextension direction of the line connecting the dual-point sound source.As another example, a method for measuring the distance between a pointsound source and the auricle, and a method for measuring the height ofthe auricle may also be adjusted according to different conditions.These similar changes may be all within the protection scope of thepresent disclosure.

FIG. 37 is a structural diagram illustrating another exemplary acousticoutput device according to some embodiments of the present disclosure.

For a human ear, a frequency band of a sound that can be heard may be ina middle-low-frequency band. An optimization goal of the acoustic outputdevice in the mid-low-frequency bands may be to increase a volume of aheard sound. When a hearing position is fixed, parameters of thedual-point sound source may be adjusted to increase the volume of theheard sound and not increase a volume of a leakage sound (e.g., anincrease of the volume of the heard sound may be greater than anincrease of the volume of the leakage sound). In a high-frequency band,a sound leakage of the dual-point sound source may be not decreasedsignificantly. In the high-frequency band, an optimization goal of theacoustic output device may be reducing the sound leakage. The soundleakage may be further reduced and a leakage-reducing frequency band maybe expanded by adjusting the parameters of the dual-point sound sourceof different frequencies. In some embodiments, the acoustic outputdevice 1000 may include an acoustic driver 1030. The acoustic driver1030 may output sound through two of the second sound guiding holes.More descriptions regarding the acoustic driver 1030, the second soundguiding holes, and a structure therebetween may be described withreference to the acoustic driver 1020 and/or the first sound guidingholes and the relevant descriptions thereof. In some embodiments, theacoustic driver 1030 and the acoustic driver 1020 may output sounds withdifferent frequencies, respectively. In some embodiments, the acousticoutput device 1000 may include a controller configured to cause theacoustic driver 1020 to output a sound within a first frequency rangeand cause the acoustic driver 1030 to output a sound within a secondfrequency range. Each frequency within the second frequency range may behigher than each frequency within the first frequency range. Forexample, the first frequency range may be 100 Hz-1000 Hz, and the secondfrequency range may be 1000 Hz-10000 Hz.

In some embodiments, the acoustic driver 1020 may be a low-frequencyspeaker, and the acoustic driver 1030 may be a middle-high-frequencyspeaker. Due to different frequency response characteristics of thelow-frequency speaker and the middle-high-frequency speaker, frequencybands of sounds output by the acoustic driver 1020 and the acousticdriver 1030 may be different. A high-frequency band and a low-frequencyband may be divided using the low-frequency speaker and themiddle-high-frequency speaker, and accordingly, a dual-point soundsource with a low-frequency and a dual-point sound source with amiddle-high-frequency may be constructed to output sound in thenear-field output and/or reduce sound leakage in the far-field. Forexample, the dual-point sound source for outputting low-frequency soundmay be formed when the acoustic driver 1020 outputs the low-frequencysound through the sound guiding hole 1011 and the sound guiding hole1012 shown in FIG. 1. The dual-point sound source with low-frequency maybe disposed on two sides of an auricle to increase a volume heard by anear near the near-field. A dual-point sound source for outputtingmiddle-high-frequency sound may be formed when the acoustic driver 1030outputs the middle-high-frequency sound through two second sound guidingholes. A middle-high-frequency sound leakage may be reduced by adjustinga distance between the two second sound guiding holes. The dual-pointsound source with middle-high-frequency may be disposed on two sides ofthe auricle, or the same side of the auricle. Alternatively, theacoustic driver 1020 may provide a dual-point sound source foroutputting full-frequency sound through the sound guiding hole 1011 andthe sound guiding hole 1012 to increase the volume of the sound in thenear-field.

Further, a distance d₂ between the two second sound guiding holes may beless than a distance d₁ between the sound guiding hole 1011 and thesound guiding hole 1012, that is, d₁ may be greater than d₂. Forillustration purposes, as shown in FIG. 9, two sets of dual-point soundsources may have a stronger sound leakage reduction capability than thatof a single point sound source and that of one single set of dual-pointsound source, and the two sets of dual-point sound sources may includeone set of a low-frequency dual-point sound source and one set of ahigh-frequency dual-point sound source, and a distance between two pointsound sources of each set of the dual-point sound sources may bedifferent.

It should be noted that the sound guiding holes of the acoustic outputdevice may be not limited to the two sound guiding holes 1011 and 1012corresponding to the acoustic driver 1720 shown in FIG. 37 distributedon two sides of the auricle, and the two sound guiding holescorresponding to the acoustic driver 1030 may be distributed on thefront side of the auricle. For example, in some embodiments, the twosecond sound guiding holes corresponding to the acoustic driver 1030 maybe disposed on the same side of the auricle (e.g., a rear side, an upperside, or a lower side of the auricle). As another example, the twosecond sound guiding holes corresponding to the acoustic driver 1030 maybe disposed on two sides of the auricle. In some embodiments, when thesound guiding holes 1011 and the sound guiding hole 1012 and/or the twosecond sound guiding holes are disposed on the same side of the auricle,a baffle may be disposed between the sound guiding holes 1011 and thesound guiding hole 1012 and/or the two second sound guiding holes tofurther increase the volume of the sound in the near-field and reducethe sound leakage in the far-field. As yet another example, the twosound guiding holes corresponding to the acoustic driver 1020 may bedisposed on the same side of the auricle (e.g., the front side, the rearside, the upper side, the lower side, etc. of the auricle).

In a practical application, the acoustic output device may includedifferent application forms such as glasses, an earphone, a bracelet, ahelmet, a watch, clothing, a backpack, etc. For illustration purposes,glasses and an earphone with a sound output function may be described asexamples of the acoustic output device in the present disclosure. Theglasses may include myopia glasses, sports glasses, hyperopia glasses,reading glasses, presbyopic glasses, sand-proof glasses, sunglasses,UV-proof glasses, welding glasses, infrared-proof glasses, virtualreality (VR) glasses, augmented reality (AR) glasses, mixed reality (MR)glasses, mediated reality glasses or the like, or a combination thereof.The earphone may include an open binaural earphone.

FIG. 38 is a schematic diagram illustrating glasses 3800 according tosome embodiments of the present disclosure. As shown in FIG. 38, theglasses 3800 may include one or more acoustic output devices 3810, oneor more frames 3820, one or more glasses legs 3830, one or more lenses3840, a communication unit 3850, a power source unit 3860, and a controlunit 3870.

The acoustic output device(s) 3810 may be configured to output sound.The sound may include audio files (e.g., music, recording, etc.),real-time calls, broadcast, prompt sound, or the like. For example, theuser may play audio or broadcast through the acoustic output devices3810. As another example, the user may make a real-time call with anexternal device through the acoustic output devices 3810 (in this case,the glasses 3800 may also include a microphone). As yet another example,the acoustic output devices 3810 may output a prompt sound according toa user's operation or a state of the glasses 3800 or one or morecomponents (e.g., the acoustic output devices 3810, the communicationunit 3850, the power source unit 3860, or the control unit 3870) of theglasses 3800. More descriptions regarding the acoustic output devices3810 may be found elsewhere in the present disclosure. See, e.g., anacoustic output device 100, an acoustic output device 300, an acousticoutput device 400, an acoustic output device 500, an acoustic outputdevice 600, an acoustic output device 1000, etc., and descriptionsthereof from FIG. 1 to FIG. 37. In some embodiments, the acoustic outputdevices 3810 may be disposed inside the temples 3830. In someembodiments, the acoustic output devices 3810 may include a first outputdevice 3810-1 and a second output device 3810-2 disposed on a lefttemple and a right temple of the temples 3830, respectively. The firstoutput device 3810-1 and the second output device 3810-2 may communicatewith a signal source (e.g., a computer, a mobile phone, or other mobiledevices) in a wired or wireless manner (e.g., Bluetooth) through thecommunication unit 3850. For example, the first output device 3810-1 andthe second output device 3810-2 may be communicated with the signalsource through the communication unit 3850. As another example, thefirst output device 3810-1 may be communicated with the signal sourcethrough the communication unit 3850, and the second output device 3810-2may be wirelessly connected with the first output device 3810-1 throughthe communication unit 3850 or may be connected with the first outputdevice 3810-1 through one or more wires inside the frames 3820 and thetemples 3830. Audio output of the first output device 3810-1 and thesecond output device 3810-2 may be synchronized through one or moresynchronization signals. In some alternative embodiments, the acousticoutput devices 3810 may be disposed inside the frames 3820 or thelens(es) 3840. In some alternative embodiments, the acoustic outputdevices 3810 may be independent of the glasses 3800 and may bedetachably connected with the glasses 3800 (e.g., via a plug connection,a snap connection, a threaded connection, etc.).

In some embodiments, each temple of the temples 3830 may carry theacoustic output devices 3810. For example, the temples 3830 may includean enclosed housing structure with a hollow interior, and the interiorof each temple of the temples 3830 may carry a plurality of first outputdevices 3810-1 or second output devices 3810-2, respectively. In someembodiments, the acoustic output devices 3810 may be disposed at a partof the temples 3830. For example, the acoustic output devices 3810 maybe disposed at a head (e.g., a part close to the lens(es) 3840), a tail(e.g., a part away from the lens(es) 3840), a middle part of the temples3830, or the like, or any combination thereof. As another example, apart of the plurality of acoustic output devices 3810 may be disposed atthe head of the temples 3830, and another part may be disposed at thetail of the temples 3830.

The glasses 3800 or the component(s) (e.g., the acoustic output devices3810, the power source unit 3860, and the control unit 3870) of theglasses 3800 may communicate with each other or with an external device(e.g., another glasses, a signal source (e.g., a computer, a mobilephone, or other mobile devices) through the communication unit 3850. Forexample, the glasses 3800 may communicate with an external mobile phone(e.g., via a Bluetooth connection manner) through the communication unit3850 to realize a function such as dialing and/or receiving a call,playing audio, etc. As another example, the glasses 3800 may communicatewith other glasses through the communication unit 3850 to realize audiosharing operation. In some embodiments, the communication between theglasses 3800 and other glasses may include wireless communication. Thewireless communication may include but is not limited to Bluetooth, alocal area network, a wide area network, a wireless personal areanetwork, a near field communication, or the like, or any combinationthereof. In some embodiments, when the communication unit 3850communicates with an external device, the external device may obtaininformation of the glasses 3800 (e.g., position information, powerinformation, etc.) and control the glasses 3800 to implement itsfunction(s), such as playing audio, making a call, or the like. In someembodiments, the communication unit 3850 may be disposed at any positionof the glasses 3800. For example, the communication unit 3850 may bedisposed inside the frames 3820, the temples 3830, or the lenses 3840.As another example, the communication unit 3850 may be integrated intothe acoustic output devices 3810, the power source unit 3860, or thecontrol unit 3870.

The frames 3820 may be configured to support the lenses 3840. In someembodiments, a shape of the frames 3820 may include a circle shape, arectangle shape, an oval shape, a polygon (regular or irregular) shape,or the like. In some embodiments, the frames 3820 may include a shapethat fits the lens(es) 3840. For example, when the lenses 3840 arerectangular, the frames 3820 may also be rectangular. As anotherexample, when the lens(es) 3840 are oval, the frames 3820 may be oval.In some embodiments, a material of the frames 3820 may include metaland/or non-metal. The metal may include pure metal (i.e., a metallicelement), alloy, metal-clad, metal-plated, or the like. The pure metalmay include iron, copper, aluminum, titanium, silver, gold, or the like.The alloy may include stainless steel, copper alloy, nickel-chromiumalloy, manganese-nickel alloy, nickel-copper alloy, nickel-titaniumalloy, titanium alloy, or the like. The metal-plated may includegold-plated, titanium-plated, rhodium-plated, palladium-plated,nickel-plated, chrome-plated, or the like. The non-metal may includeplastic, fiber (e.g., acetate, nitrocellulose, nylon), polymer material(e.g., plastic titanium, epoxy resin), wood, an animal shell, an animalhorn, or the like. The plastic may include thermoplastic, thermosettingplastic, hybrid plastic, or the like. In some embodiments, the materialof the temples 3830 may be the same as the material of the frames 3820.For example, the material of the temples 3830 and the material of theframes 3820 may be both plastic titanium. In some alternativeembodiments, the material of the temples 3830 may be different from thematerial of the frames 3820. For example, the material of the temples3830 may be plastic, and the material of the frames 3820 may be metal.

In some embodiments, the glasses 3800 may further include a bridge 3821.The bridge 3821 may connect the left and right frames 3820 and the leftand right lenses 3840. The bridge 3821 may be integrally formed with theleft and right frames 3820 or physically connected between a left frameand a right frame of the frames 3820. The material of the bridge 3821may be the same as or different from that of the frames 3820. In someembodiments, the glasses 3800 may further include one or more nose pads3822. The nose pad(s) 3822 may be configured to support and stabilizethe glasses 3800 when the user wears the glasses 3800. A left nose padand a right nose pad of the nose pads 3822 may be integrally formed withthe left and right lens frames 3820 or physically connected to the leftand right frames of the frames 3820, respectively. The material of thenose pad(s) 3822 may be the same as or different from that of the frames3820. In some embodiments, the frames 3820 may further include one ormore pile heads 3823. The pile heads 3823 may be a junction between theframes 3820 and the temples 3830. The frames 3820 may be physicallyconnected to the temples 3830 through the pile heads 3823. The physicalconnection may include a hinged connection, a snap connection, athreaded connection, a welding connection, or the like. For example, oneend of a hinge 3880 configured to connect a frame of the frames 3820 anda temple of the temples 3830 may be fixed at the pile heads 3823 and theother end of the hinge 3880 may be fixed at the temples 3830. A leftpile head and a right pile head of the pile heads 3823 may be integrallyformed with the left frame and the right frame of the frames 3820 orphysically connected to the left and right frames of the frames 3820,respectively. Material of the pile heads 3823 may be the same as ordifferent from that of the frames 3820. Material of the hinge 3880 mayinclude pure metal, alloy, metal-clad, metal-plated (e.g., metal-platedstainless steel), or the like.

In some embodiments, a shape of the lens(es) 3840 may include a circleshape, a rectangle shape, an oval shape, a polygon (regular orirregular) shape, or the like. In some embodiments, the lens(es) 3840may include a myopia lens, a presbyopic lens, a sunglass lens (e.g., adark glasses), a flat lens, an anti-blue lens, a polarized lens, or thelike, or any combination thereof. Material of the lens(es) 3840 mayinclude natural material, optical glass, optical resin, or the like. Insome embodiments, the lens(es) 3840 may have anti-scratch andanti-shatter performance. In some embodiments, the glasses 3800 may beused as augmented reality (AR) glasses or virtual reality (VR) glasses.In this case, the light transmittance and/or haze degree of the lens(es)3840 may be automatically adjusted and the glasses 3800 may call a miniprojection device near the lens(es) 3840. For example, in an AR mode,the light transmittance of the lens(es) 3840 may be reduced, and animage or a video to be projected may be projected outside the lens(es)3840 in a user's gaze direction through the mini projection device. Asanother example, in an VR mode, the haze degree of the lens(es) 3840 maybe increased, and an image or a video to be projected may be projectedinside the lens(es) 3840 through the mini projection device.

The power source unit 3860 may be configured to provide electrical powerto other components (e.g., the acoustic output devices 3810, thecommunication unit 3850, or the control unit 3870) of the glasses 3800.In some embodiments, a charging mode of the power source 3860 mayinclude a wireless charging mode, a wired charging mode, a magneticcharging mode, or the like. The wireless charging mode may include anelectromagnetic induction wireless charging mode, a magnetic resonancewireless charging mode, a radio wave wireless charging mode, a solarcharging mode, or the like, or any combination thereof. In someembodiments, the power source unit 3860 may include a dry battery, alead storage battery, a lithium battery, a solar battery, or the like,or any combination thereof. In some embodiments, the power source unit3860 may be disposed inside the temples 3830. For example, the powersource unit 3860 may be disposed inside the left temple or the righttemple of the temples 3830, and may provide electrical power to thefirst output device 3810-1 and the second output device 3810-2 of thetemples 3830. As another example, the power source unit 3860 may bedisposed inside the left temple and the right temple of the temples3830, and may provide electrical power to the first output device 3810-1and the second output device 3810-2, respectively. It should be notedthat the power source unit 3860 is not limited to the case shown in FIG.38 that the power source unit 3860 is disposed at a position of thetemples 3830 close to the lenses 3840. For example, the power sourceunit 3860 may be disposed at a position of the temples 3830 away fromthe lenses 3840. As another example, the power source unit 3860 may bedisposed inside the frames 3820 or the lens(es) 3840. As yet anotherexample, the power source unit 3860 may be integrated into the acousticoutput devices 3810, the communication unit 3850, the control unit 3870,etc.

The control unit 3870 may be configured to control a working state ofthe one or more components (e.g., the acoustic output devices 3810, thecommunication unit 3850, the power source unit 3860, etc.) of theglasses 3800. For example, the control unit 3870 may control theacoustic output devices 3810 to turn on or off. As another example, thecontrol unit 3870 may switch audio outputted by the acoustic outputdevices 3810 according to a user's instruction, for example, playingaudio, playing songs in a playlist of a specified category (e.g., aclassical category, a pop category), or playing songs of a specifiedsinger (e.g., Michael Jackson, Jay Chou, etc.), adjusting the volume ofsound outputted by the acoustics output devices 3810, etc. In someembodiments, the control unit 3870 may communicate with the component(s)of the glasses 3800 directly or through the communication unit 3850. Insome embodiments, the control unit 3870 may automatically detectstate(s) of component(s) of the glasses 3800 or automatically receivestate information reported by the component(s) of the glasses 3800.According to the state or state information, the control unit 3870 maycontrol the component(s) of the glasses 3800. For example, the controlunit 3870 may automatically detect the electric quantity of the powersource 3860, and when the electric quantity of the power source 3860 islower than a critical value (e.g., 20%), the control unit 3870 maycontrol the acoustic output device 3810 to output a charging promptsound (e.g., “Low Battery”, “Power Off”). As another example, thecontrol unit 3870 may automatically detect whether the communicationunit 3850 is connected to an external device (e.g., the user's mobilephone) (e.g., via a Bluetooth manner). When the communication unit 3850is not connected to the external device, the control unit 3870 maycontrol the communication unit 3850 to connect the external device andcontrol the acoustic output devices 3810 to output a prompt sound whenthe connection is successful (e.g., “Bluetooth Connected”). In someembodiments, the control unit 3870 may be further configured to controlan external device that communicates with the glasses 3800. For example,the control unit 3870 may control a smart assistant (e.g., SIRI™) in amobile phone associated with the glasses 3800 through the communicationunit 3850. Further, according to the user's instruction (e.g., a voiceinstruction, a tapping instruction, etc.), the control unit 3870 maywake up the smart assistant in the mobile phone through thecommunication unit 3850, and control the mobile phone to perform anoperation through the smart assistant, such as checking the weather,starting navigation, voice control playback, etc. In some embodiments,the control unit 3870 may be disposed at any position of the temples3830, the frames 3820, or the lenses 3840. In some alternativeembodiments, the control unit 3870 may be integrated into the acousticoutput devices 3810, the communication unit 3850, or the power sourceunit 3860.

In some embodiments, the glasses 3800 may include an acoustic receivingdevice (not shown). The acoustic receiving device may be configured toreceive an external sound, such as a user's voice instruction, a call,or the like. The acoustic receiving device may include a microphone, avoice tube, or the like. The acoustic receiving device may be disposedat any position of the temples 3830, the frames 3820, or the lenses3840. In some alternative embodiments, the acoustic receiving device maybe integrated into the acoustic output devices 3810, the communicationunit 3850, the power source unit 3860, or the control unit 3870.

In some embodiments, the glasses 3800 may further include one or moredetection units (not shown). The detection unit(s) may be configured toautomatically detect the working state of the glasses 3800 and thecomponent(s) (e.g., the acoustic output devices 3810, the communicationunit 3850, or the power source(s) 3860) of the glasses 3800. In someembodiments, the control unit 3870 may control the glasses 3800 and thecomponent(s) of the glasses 3800 according to the state informationdetected by the detection unit(s) (e.g., a placement or wearing state,whether being rapped, a tilt angle, an electric quantity, etc.). Forexample, when the detection unit(s) detects that the glasses 3800 are ina removed state, the control unit 3870 may turn off the component(s)(e.g., the acoustic output devices 3810) of the glasses 3800 after apreset time (e.g., 15 s). As another example, when the detection unit(s)detects that one of the temples 3830 of the glasses 3800 is rappedregularly (e.g., two beats in rapid succession), the control unit 3870may automatically pause the acoustic output device 3810 to output sound.As yet another example, when detecting that the power source unit 3860is with insufficient electrical power, the control unit 3870 may controlthe acoustic output device 3810 to output a prompt sound that theglasses needs to be charged. The detection unit(s) may be disposed atany position of the temples 3830, the frames 3820, or the lenses 3840.The detection unit(s) may include a detector, a sensor, a gyroscope, orthe like. The detector may include a battery detector, a weightdetector, an infrared detector, a mechanical detector, or the like, orany combination thereof. The sensor may include a temperature sensor, ahumidity sensor, a pressure sensor, a displacement sensor, a flowsensor, a liquid level sensor, a force sensor, a speed sensor, a torquesensor, or the like, or any combination thereof. The gyroscope may beconfigured to detect a placement direction of the glasses 3800. Forexample, when the gyroscope detects that a bottom of the glasses 3800 isplaced upward, the control unit 3870 may turn off the power source unit3860 after a preset time (e.g., 20 s). The gyroscope may alsocommunicate with a gyroscope of an external device (e.g., a mobilephone) directly or through the communication unit 3850.

In some embodiments, the glasses 3800 may include a control switch (notshown). The control switch may be configured to directly control theglasses 3800 and the component(s) (e.g., the acoustic output devices3810, the communication unit 3850, or the power source unit 3860) of theglasses 3800. The form and operation mode of the control switch aremerely described as some examples. A user may control the glasses 3800or the component(s) of the glasses 3800 by performing an operation onone or more buttons of the control switch. The operation may include asimultaneously pressing, a sequentially multiple consecutive pressing, asingle short-time pressing, a single long-time pressing, a touching, asliding, or the like, or any combination thereof. For example, the usermay turn on or off the acoustic output device 3810 by pressing thecontrol button for a long time. As another example, the user may connector disconnect the communication (e.g., a Bluetooth connection) betweenthe glasses 3800 and an external device by pressing the control switchfor a long time. As yet another example, the user may answer or hang upa call, play or pause audio, switch audio (e.g., play next audio or playprevious audio) by clicking the control switch for different times. Insome embodiments, the user may control an external device communicating(or associated) with the glasses 3800 by performing an operation on oneor more buttons in the control switch. The operation may include asimultaneously pressing, sequentially multiple consecutive pressing, asingle short-time pressing, a single long-time pressing, a touching, asliding, or the like, or any combination thereof. For example, when theuser presses the control switch, the control switch may wake up thesmart assistant in the mobile phone directly or through thecommunication unit 3850. As another example, when the detection unit(s)detects that the control switch is pressed, the control unit 3870 maywake up the smart assistant in the mobile phone. The control switch mayinclude a physical button, an optical button, an electronic button, orthe like. The control switch may be disposed at any position of thetemples 3830, the frames 3820, or the lenses 3840.

In some embodiments, the glasses 3800 may include one or more indicatorlights (not shown). The indicator lights may be configured to indicatethe working state of the components (e.g., the acoustic output devices3810, the communication unit 3850, or the power source unit 3860) of theglasses 3800. The indicator lights may emit light of one or more colorsand/or flash different times to indicate different states (e.g., on,off, volume, power, tone, voice rate, etc.) of the acoustic outputdevices 3810. For example, when the acoustic output device 3810 isturned on, at least one of the indicator lights may emit green light,and when the acoustic output device 3810 is turned off, at least one ofthe indicator lights may emit red light. As another example, when theacoustic output device 3810 is turned on, at least one of the indicatorlights may flash 3 times, and when the acoustic output device 3810 isturned off, at least one of the indicator lights may flash once. Theindicator lights may also emit light with one or more colors and/orflash different times to indicate a connection state of thecommunication unit 3850. For example, when the communication unit 3850is successfully connected to an external device, at least one of theindicator lights may emit green light, and when the communication unit3850 is disconnected from the external device, at least one of theindicator lights may emit red light. As another example, when thecommunication unit 3850 is disconnected from the external device, atleast one of the indicator lights may keep flashing. The indicatorlights may emit light with one or more colors and/or flash differenttimes to indicate the electric quantity of the power source 3860. Forexample, when the power source 3860 lacks electricity, at least one ofthe indicator lights may emit red light. As another example, when thepower source 3860 lacks electricity, at least one of the indicatorlights may keep flashing. The indicator lights may be disposed at anyposition of the temples 3830, the frames 3820, or the lens(es) 3840.

In some embodiments, the glasses 3800 may include a positioning unit(not shown). The positioning unit may be configured to obtain real-timeposition information of the glasses 3800. Exemplary position informationmay include longitude data, latitude data, location information,surrounding environment information, or the like, or any combinationthereof. The positioning unit may position the glasses 3800 through aGlobal Positioning System (GPS), a Global Navigation Satellite System(GLONASS), a Beidou Navigation System (COMPASS), a Galileo PositioningSystem, a Quasi-Zenith Satellite System (QZSS), and a Wireless Fidelity(Wi-Fi) positioning technology, or the like, or any combination thereof.In some embodiments, an external device communicating with the glasses3800 may obtain the position information of the glasses 3800.

In some embodiments, the glasses 3800 may have a waterproof rating ofIPX1, IPX2, IPX3, IPX4, IPX5, IPX6, IPX7, IPX8, etc. In someembodiments, the glasses 3800 may have a dustproof rating of IP1, IP2,IP3, IP4, IP5, IP6, etc.

It should be noted that the above description is merely for theconvenience of description, and not intended to limit the scope of thepresent disclosure. It should be understood that, for those skilled inthe art, after understanding the principle of the present disclosure,various modifications and changes in the forms and details of theglasses 3800 may be made without departing from this principle. Forexample, the glasses 3800 may further include other units, such as anoise reduction unit. The noise reduction unit may be configured toreduce the noise of the sound output by the acoustic output device 3810.These changes are within the protection scope of the present disclosure.

FIG. 39 is a schematic diagram illustrating a cross-sectional view of atemple of the glasses 3800 according to some embodiments of the presentdisclosure. As shown in FIG. 39, the temple 3830 may include a cavity3910. The acoustic output device 3810 may be disposed in the cavity3910. The acoustic output device 3810 may include an acoustic route 3920and an acoustic driver 3930 disposed in the acoustic route 3920. In someembodiments, the acoustic route 3920 may include a shell structure withvarious shapes. The shape of the acoustic route 3920 may include acircular ring, a rectangle, an oval, a (regular or irregular) polygon, aU-shape, a V-shape, a semi-circle, etc. In some embodiments, theacoustic route 3920 may be a part of the temple 3830 or physicallyconnected to the temple 3830 (e.g., via a snap connection, a threadedconnection, etc.). In some embodiments, the acoustic route 3920 mayinclude a guiding tube, a sound cavity, a resonant cavity, a sound hole,a sound slit, a tuning net, or the like, or any combination thereof.More descriptions regarding the acoustic output device 3810 may be foundelsewhere in the present disclosure. See, e.g., FIG. FIG. 4, FIG. 5,FIGS. 6A-6B, FIGS. 7A-7B, FIG. 10, and FIG. 37, and the relevantdescriptions thereof.

In some embodiments, the acoustic route 3920 may include a guiding tubewith a certain size. The size may be denoted by one or more parameterssuch as a tube radius, a length, an aspect ratio, etc. In someembodiments, the tube radius of the acoustic route 3920 may remainunchanged or may be changed along the length of the acoustic route 3920.In some embodiments, the tube radius of the acoustic route 3920 may belarger than or equal to 5.0 millimeters, 4.5 millimeters, 4.0millimeters, 3.5 millimeters, 3.0 millimeters, 2.5 millimeters, 2.0millimeters, 1.5 millimeters, 1.0 millimeters, 0.5 millimeters, etc. Insome embodiments, the tube radius of the acoustic route 3920 may be lessthan or equal to 9.0 millimeters, 8.5 millimeters, 8.0 millimeters, 7.5millimeters, 7.0 millimeters, 6.5 millimeters, 6.0 millimeters, 5.5millimeters. In some embodiments, the length of the acoustic route 3920may be less than or equal to 500 millimeters, 450 millimeters, 400millimeters, 350 millimeters, 300 millimeters, 250 millimeters, 200millimeters, 150 millimeters, 100 millimeters, 50 millimeters, 30millimeters, 10 millimeters, etc. In some embodiments, the aspect ratio(a length to a radius) of the acoustic route 3920 may be less than orequal to 200, 150, 100, 50, etc. More descriptions regarding theacoustic route 3920 may be found elsewhere in the present disclosure.See, e.g., FIG. 4, FIG. 5, FIGS. 6A-6B, and FIGS. 8A-8C, and therelevant descriptions thereof.

The acoustic route 3920 may include one or more guiding holes 3940(e.g., a guiding hole 3940-1 and a guiding hole 3940-2) for transmittingsound, and the acoustic driver 3930 may output sound through the guidinghole 3940-1 and the guiding hole 3940-2. In some embodiments, theguiding hole 3940-1 and the guiding hole 3940-2 may be respectivelydisposed on a surface 3950 of the temple 3830 and directly communicatedwith the external environment. In this case, the guiding hole(s) 3940for outputting sound in the acoustic output device 3810 may be disposedon the temple 3830. When the user wears the glasses 3800, the guidinghole 3940 may be close to but not block the ear canal, and the user'sears remain open. The user may not only hear the sound outputted by theacoustic output device 3810, but also obtain the sound of the externalenvironment. In some embodiments, a shape of the guiding hole(s) 3940may include a circle, a circular ring, rectangle, an oval, a (regular orirregular) polygon, a U-shape, a V-shape, semi-circle, or the like. Theshape of the guiding hole 3940-1 may be the same as or different fromthat of the guiding hole 3940-2. Merely by way of example, the guidinghole 3940-1 and the guiding hole 3940-2 may be circular. One of theguiding holes may be circular, and the other of the guiding holes may beoval. In some embodiments, the guiding hole 3940 may have a certainsize. The size of the guiding hole 3940-1 may be the same as ordifferent from that of the guiding hole 3940-2. In some embodiments, theguiding hole may be referred to as a sound source (although the acousticdriver 3930 may actually output the sound from a view of physics). Aguiding hole 3940 may be regarded as a point sound source (or a singlepoint sound source). A pair of the guiding holes 3940 (e.g., the guidinghole 3940-1 and the guiding hole 3940-2) corresponding to the sameacoustic driver 3930 may be regarded as a dual-point sound source. Insome embodiments, an area of each guiding hole may be less than or equalto 2 cm², 1.5 cm², 1.2 cm², 1 cm², 0.8 cm², 0.5 cm², 0.3 cm², 0.2 cm²,0.1 cm², 0.05 cm², etc. In some embodiments, the area of some guidingholes may be less than or equal to 0.3 cm², and the area of a part ofsome guiding holes may be larger than or equal to 0.3 cm². In someembodiments, the area of some guiding holes may be less than or equal to0.2 cm², and the area of some guiding holes may be larger than or equalto 0.2 cm². In some embodiments, the area of some guiding holes may beless than or equal to 0.1 cm², and the area of some guiding holes may belarger than or equal to 0.3 cm².

In some embodiments, the acoustic route 3920 may carry one or moreacoustic drivers 3930. The acoustic driver(s) 3930 may be disposedinside the acoustic route 3920. The acoustic driver(s) 3930 may be acomponent that may receive an electrical signal and convert theelectrical signal into a voice signal to be output. In some embodiments,according to a frequency, a type of the acoustic driver 3930 may includea low-frequency acoustic driver, a high-frequency acoustic driver, afull-frequency acoustic driver, or any combination thereof. In someembodiments, according to a principle, the acoustic driver 3930 mayinclude a moving coil driver, a moving iron driver, a piezoelectricdriver, an electrostatic driver, a magnetostrictive driver, or the like.More descriptions regarding the acoustic driver 3930 may be foundelsewhere in the present disclosure. See, e.g., FIG. 4, FIG. 5, FIGS.6A-6B, FIG. 10, and FIG. 37, and the relevant descriptions thereof.

In some embodiments, the acoustic driver 3930 may include a transducer.The transducer may be configured to generate vibration under the drivingof an electric signal, and the vibration may generate sounds with thesame amplitude, the same frequency, and opposite phases (180 degreesinversion). A type of the transducer may include an air conductiveloudspeaker, a bone conductive loudspeaker, a hydroacoustic transducer,an ultrasonic transducer, or the like, or any combination thereof. Thetransducer may be of a moving coil type, a moving iron type, apiezoelectric type, an electrostatic type, a magnetostrictive type, orthe like, or any combination thereof. More descriptions regarding thesound guiding hole 3940 may be found elsewhere in the presentdisclosure. See, e.g., FIG. 4, FIG. 5, and FIGS. 6A-6B, and the relevantdescriptions thereof.

In some embodiments, the transducer may include a vibration diaphragm.The vibration diaphragm may vibrate when driven by an electric signal,and a front side and a rear side of the vibration diaphragm maysimultaneously output a positive phase sound and a reverse phase sound.In some embodiments, a front chamber (i.e., a front half of the acousticroute 3920) for transmitting sound may be provided at the front side ofthe vibration diaphragm in the acoustic route 3920. The front chambermay be acoustically coupled with the guiding hole 3940-1, and the soundfrom the front side of the vibration diaphragm may be output from theguiding hole 3940-1 through the front chamber. A rear chamber (i.e., arear half of the acoustic route 3920) for transmitting sound may beprovided at the rear side of the vibration diaphragm in the acousticroute 3920. The rear chamber may be acoustically coupled with theguiding hole 3940-2, and the sound from the rear side of the vibrationdiaphragm may be output from the guiding hole 3940-2 through the rearchamber. It should be noted that when the vibration diaphragm isvibrating, the front side and the rear side of the vibration diaphragmmay simultaneously generate sounds with opposite phases. When the soundspass through the front chamber and the rear chamber, respectively, thesounds may propagate outwards from the guiding hole 3940-1 and theguiding hole 3940-2. In some embodiments, the structures of the frontchamber and the rear chamber may be designed so that the sound output bythe acoustic driver 3930 at the sound guiding hole 3940-1 and the soundguiding hole 3940-2 may satisfy a specific condition. For example,lengths of the front chamber and the rear chamber may be designed suchthat sounds with a specific phase relationship (e.g., opposite phase)(in the figure, “+” and “−” may be configured to represent sounds withdifferent phases) may be output from the guiding hole 3940-1 and theguiding hole 3940-2. Accordingly, a low volume in the near-field of theglasses may be improved and sound leakage in the far-field may beeffectively reduced. More descriptions regarding the sound leakagereduction of the dual-point sound source may be found elsewhere in thepresent disclosure. See, e.g., FIG. 2 and the relevant descriptionsthereof.

In some embodiments, a plurality of front chambers for transmittingsound may be provided at the front side of the vibration diaphragm inthe acoustic route 3920, and each of the plurality of front chambers maybe coupled with the guiding hole 3940-1 corresponding to the frontchamber. A plurality of rear chambers for transmitting sound may beprovided at the rear side of the vibration diaphragm in the acousticroute 3920. Each of the plurality of rear chambers may be coupled withthe guiding hole 3940-2 corresponding to the rear chamber. For example,the acoustic route 3920 may include two front chambers beside the frontside of the vibration diaphragm. When the vibration diaphragm vibrates,the sound generated on the front side of the vibration diaphragm may betransmitted to the two corresponding guiding holes 3940-1, respectively,through the two front chambers. The two guiding holes 3940-1corresponding to the front side of the vibration diaphragm and the oneguiding hole 3940-2 corresponding to the rear chamber of the vibrationdiaphragm may form a tri-point sound source.

In some embodiments, the acoustic driver 3930 may include a plurality ofvibration diaphragms (e.g., two vibration diaphragms). Each of theplurality of vibration diaphragms may vibrate to generate sound, whichmay pass through different chambers connected to the vibration diaphragmin the acoustic route 3920 and output from corresponding guiding hole3940. The plurality of vibration diaphragms may be controlled by thesame or different controllers, and generate sounds that satisfy certainphases and amplitudes (e.g., sounds with the same amplitude but oppositephases, sounds with different amplitudes and opposite phases, etc.).More descriptions regarding the vibration diaphragm may be foundelsewhere in the present disclosure. See, e.g., FIG. FIG. 1, FIG. 5, andFIG. 10, and the relevant descriptions thereof.

In some embodiments, the sound generated by the plurality of vibrationdiaphragms may be decomposed into two or more sounds having differentfrequency components. For example, the sound may be decomposed into asound having high-frequency components and a sound having low-frequencycomponents. The sounds having different frequency components may betransmitted to the corresponding guiding hole 3940. For example, thesound with the high-frequency components may be transmitted to theguiding holes 3940-1 and 3940-2 and propagated outwards through theguiding holes 3940-1 and 3940-2, and the sound with the low-frequencycomponents may be transmitted to the guiding holes 3940-3 and 3940-4(not shown) and propagate outwards through the guiding holes 3940-3 and3940-4. More descriptions regarding the frequency division may be foundelsewhere in the present disclosure. See, e.g., FIG. 2, FIG. 4, andFIGS. 8A-8C, and the relevant descriptions thereof.

In some embodiments, the acoustic route 3920 may include a tuning netand/or tuning cotton to adjust the sound output by the acoustic driver3930. In some embodiments, each guiding hole 3940 may include asound-permeable dust-proof net and/or a waterproof net to protectcomponents inside the temple 3830 of the glasses 3800. The dust-proofnet and/or the waterproof net may be of high-density net cover material.These changes may fall within the protection scope of the presentdisclosure.

FIG. 40 is a schematic diagram illustrating guiding holes on a temple ofa glasses 3800 according to some embodiments of the present disclosure.As shown in FIG. 40, a guiding hole 3940-1 and a guiding hole 3940-2 ofan acoustic output device 3810 may be disposed on a lower side 3831 of atemple 3830. The guiding hole 3940-1 may be disposed on the temple 3830and at a rear side of the user's auricle when the glasses is worn by theuser. The guiding hole 3940-2 may be disposed on the temple 3830 and ata front side of the user's auricle when the glasses is worn by the user.When the guiding hole 3940-1 and the guiding hole 3940-2 of the acousticoutput device 3810 are disposed on both sides of the auricle,respectively, the auricle may serve as a baffle. In this case, theguiding hole 3940-1 and the guiding hole 3940-2 may be respectivelyregarded as a point sound source A1 and a point sound source A2 in FIG.40, and the auricle may be equivalent to the baffle in FIG. 40. Ahearing position A0 may be a position of the ear hole.

It should be noted that the guiding hole(s) 3940 (e.g., the guiding hole3940-1 and the guiding hole 3940-2) of the acoustic output device 3810are not limited to the distribution shown in FIG. 40. For example, theguiding hole 3940-1 may be disposed on a front side of the user'sauricle, and an upper side 3834, an inner side 3832, or an outer side3833 of the temple 3830, when the glasses is worn by the user. Theguiding hole 3940-2 may be disposed on the rear side of the user'sauricle and the upper side 3834, the inner side 3832, or the outer side3833 of the temple 3830 when the glasses is worn by the user. In someembodiments, when the guiding holes 3940-1 and 3940-2 are disposed onthe front side of the user's auricle and on a surface 3950 of the temple3830 when the glasses are worn by the user, the auricle may not serve asa baffle. In the embodiment, a baffle may be disposed between theguiding holes 3940-1 and 3940-2. The baffle may be disposed inside thetemple 3830 or on the outer surface of the temple 3830. Moredescriptions regarding the baffle may be found elsewhere in the presentdisclosure. See, e.g., FIG. 14, FIGS. 18-21, and FIGS. 29-36, and therelevant descriptions thereof.

In some embodiments, a count of the guiding hole 3940-1 or 3940-2 onboth sides of the user's auricle and on the temple 3830 when the glassesare worn by the user may be not limited to one shown in FIG. 40, and thecount of the guiding hole 3940-1 or 3940-2 may be any integer than 1.The count of the guiding hole 3940-1 may be the same as or differentfrom that of the guiding hole 3940-2. For example, the count of theguiding holes 3940-2 on the front side of the user's auricle and on thetemple 3830 may be two, and the count of the guiding holes 3940-1 on therear side of the user's auricle and on the temple 3830 may be two orthree. These changes are fall within the protection scope of the presentdisclosure.

FIG. 41 is a schematic diagram illustrating a cross-sectional view of atemple of glasses 3800 according to some embodiments of the presentdisclosure. As shown in FIG. 41, an acoustic output device 3810 mayinclude an acoustic driver 4130. The acoustic driver 4130 may outputsound from two corresponding guiding holes 4140 (e.g., a guiding hole4140-1 and a guiding hole 4140-2). In some embodiments, the acousticdriver 4130 and the acoustic driver 3930 may respectively output soundswith different frequencies. In some embodiments, the acoustic outputdevice 3810 may further include a controller (not shown), and thecontroller may be configured to cause the acoustic driver 3930 to outputsound in a first frequency range and cause the acoustic driver 4130 tooutput sound in a second frequency range. The second frequency range mayinclude frequencies higher than frequencies in the first frequencyrange. For example, the first frequency range may be 100 Hz-1000 Hz, andthe second frequency range may be 1000 Hz-10000 Hz. In some alternativeembodiments, the controller may be configured to cause the acousticdriver 3930 to output sounds in a plurality of frequency ranges (e.g., alow frequency range, a low and middle frequency range, a middle and highfrequency range, a high frequency range, etc.). More descriptionsregarding the controller may be found elsewhere in the presentdisclosure. See, e.g., FIG. 4, FIGS. 6A-6B, and FIG. 37, and therelevant descriptions thereof.

In some embodiments, the acoustic driver 3930 may be a low-frequencyacoustic driver, and the acoustic driver 4130 may be a high-frequencyacoustic driver. For example, the acoustic driver 3930 may be alow-frequency loudspeaker (e.g., a moving coil driver), and the acousticdriver 4130 may be a high-frequency loudspeaker (e.g., a moving irondriver). Due to different frequency response characteristics of thelow-frequency loudspeaker and the high-frequency loudspeaker, frequencybands (or ranges) of the output sound may be different. High-frequencybands and low-frequency bands of a sound may be divided using thelow-frequency loudspeaker and the high-frequency loudspeaker. Alow-frequency dual-point sound source and a high-frequency dual-pointsound source may be constructed to improve a volume of the sound in thenear-field and reduce far-field sound leakage. For example, the acousticdriver 3930 may provide a dual-point sound source for outputting alow-frequency sound through the guiding hole 3940-1 and the guiding hole3940-2, which may be configured to output sound in the low-frequencyband. The low-frequency dual-point sound source may be closer to theauricle and configured to increase a volume near the near-field (e.g.,positions near the ear of the user). The acoustic driver 4130 mayprovide a dual-point sound source for outputting a high-frequency soundthrough the guiding hole 4140-1 and the guiding hole 4140-2, which maybe configured to output sound in the high-frequency band. Moredescriptions regarding the construction of the low-frequency dual-pointsource and the high-frequency dual-point sound source and positions ofthe low-frequency dual-point source and the high-frequency dual-pointsound source may be found elsewhere in the present disclosure. See,e.g., FIG. 42 and the relevant descriptions thereof. In someembodiments, the acoustic driver 4130 may provide a dual-point soundsource for outputting a full-frequency sound through the guiding hole4140-1 and the guiding hole 4140-2, thereby further increasing thevolume of the near-field sound. In some alternative embodiments, theacoustic output device 3810 may include a plurality of acoustic drivers3930 for generating sounds in a plurality of frequency bands (e.g., alow frequency band, a middle and low frequency band, a middle and highfrequency band, a high frequency band, etc.).

For human ears, the frequency band of sound that can be heard may beconcentrated in a low-frequency band, and in the low-frequency band, thedual-point sound source may have a strong sound leakage reductioneffect, thus in the low-frequency band, an optimization goal may be toincrease a volume of the hearing sound. In the high-frequency band, thesound leakage reduction effect of the dual-point sound source may berelatively weak. In the high-frequency band, an optimization goal may beto reduce sound leakage. In some embodiments, the effect of increasingthe volume of the hearing sound, reducing the volume of leakage sound(e.g., the increment of the volume of the hearing sound is greater thanthe increment of the volume of the leakage sound), and expanding thefrequency band of leakage reduction may be achieved by adjustingparameters of the acoustic output device 3810 (e.g., a distance betweenthe guiding holes, a frequency band of the output sound, a distancebetween the front chamber and the rear chamber in the acoustic route3920 and the acoustic route 4120, and an acoustic impedance in a frontand a rear of the diaphragm).

In some embodiments, the acoustic driver 3930 may be a mid-low-frequencyloudspeaker that outputs sound in the mid-low-frequency band. In someembodiments, the acoustic driver 4130 may be a mid-high-frequencyloudspeaker that outputs sound in the mid-high-frequency band. Thesechanges are within the protection scope of the present disclosure.

FIG. 42 is a schematic diagram illustrating guiding holes on a temple ofa glasses according to some embodiments of the present disclosure. Asshown in FIG. 41 and FIG. 42, the guiding holes 4140 (e.g., the soundguiding hole 4140-1 and the sound guiding hole 4140-2) corresponding tothe acoustic driver 4130 in the acoustic output device 3810 may bedisposed on the lower side 3831 of the temple 3830. For the purposes ofillustration, the following descriptions are described assuming that theacoustic driver 4130 is a high-frequency acoustic driver and theacoustic driver 3930 is a low-frequency acoustic driver, and notintended to limit the scope of the present disclosure. In someembodiments, distances between two sets of guiding holes 3940 and 4140may be controlled to increase a volume of the near-field sound andreduce high-frequency sound leakage. In some embodiments, a distance d₂between the guiding hole 4140-1 and the guiding hole 4140-2corresponding to the acoustic driver 4130 may be less than a distance d₁between the guiding hole 3940-1 and the guiding hole 3940-2corresponding to the acoustic driver 3930, that is, d₁ may be greaterthan d₂. In the low-frequency band, a relatively great distance d₁ maycorrespond to a relatively high volume output by the acoustic outputdevice 3810. At the same time, the relatively great distance d₁ mayslightly increase the sound leakage, the sound leakage in thelow-frequency band may be very relatively small, and after slightlyincreased, the leakage sound may be kept at a low level. In the highfrequency band, a relatively small distance d₂ may overcome a problemthat a cut-off frequency of the high-frequency sound leakage reductionis relatively low and the frequency band of the sound leakage reductionis relatively narrow. On the other hand, the relatively small distanced₂ may improve the sound leakage reduction performance of the acousticoutput device in the high-frequency band, and satisfy the needs of anopen binaural acoustic output device. More descriptions regarding theadjustment of the distance between two point sound sources of adual-point sound source to reduce sound leakage may be found elsewherein the present disclosure. See, e.g., FIG. 9 and FIGS. 12-13, and therelevant descriptions thereof.

In some embodiments, the frequency band of the sound output by theguiding hole 3940-1 and the guiding hole 3940-2 corresponding to theacoustic driver 3930 may overlap with the frequency band of the soundoutput by the guiding hole 4140-1 and the guiding hole 4140-2corresponding to the acoustic driver 4130. In this embodiment, a phaseof the sound output by the guiding hole 3940 (also referred to as aphase of the guiding hole) corresponding to the acoustic driver 3930 maybe the same as or different from a phase of the sound output by theguiding hole 4140 corresponding to the acoustic driver 4130. When thephase of the guiding hole 3940 is different from the phase of theguiding hole 4140, the sound leakage reduction of the glasses may beimproved. In some embodiments, when the frequency band of the soundoutput by the guiding hole 3940-1 and the guiding hole 3940-2 overlapswith the frequency band of the sound output by the guiding hole 4140-1and the guiding hole 4140-2, and the phase of the guiding hole 3940 isdifferent from the phase of the guiding hole 4140, d₁/d₂ may be set to1-1.5, 1-1.4, 1-1.3, 1-1.2, 1-1.1, etc. More descriptions regarding theoverlap of the frequency bands may be found elsewhere in the presentdisclosure. See, e.g., FIG. 4 and the relevant descriptions thereof.

In some embodiments, the sound leakage may be reduced by controlling thelength of the front chamber and the rear chamber corresponding to theguiding hole. For example, a length of the rear chamber corresponding tothe guiding hole 3940-2 may be different from a length of the frontchamber corresponding to the guiding hole 3940-1, and a length of therear chamber corresponding to the guiding hole 4140-2 may be the same asa length of the front chamber corresponding to the guiding hole 4140-1,and a phase difference between the two sounds output by the guidingholes (e.g., the guiding hole 3940 and the guiding hole 4140) may be180°. In this embodiment, a ratio of the length of the rear chambercorresponding to the guiding hole 3940-2 to the length of the frontchamber corresponding to the guiding hole 3940-1 may be 0.5-2, 0.6-1.5,0.8-1.2, etc. More descriptions regarding the adjustment of the lengthsof the front chamber and the rear chamber to reduce sound leakage may befound elsewhere in the present disclosure. See, e.g., FIGS. 34-36 andthe relevant descriptions thereof.

In some embodiments, the sound leakage may be reduced by controllingacoustic impedances at the front and the rear of the diaphragm. In someembodiments, an acoustic impedance of an acoustic route (e.g., the frontchamber) corresponding to the guiding hole 3940-2 may be different froman acoustic impedance of the acoustic route (e.g., the rear chamber)corresponding to the guiding hole 3940-1 in the acoustic output device3810, and an acoustic impedance of the acoustic route (e.g., the frontchamber) corresponding to the guiding hole 4140-2 may be different fromthe acoustic impedance of the acoustic route (e.g., the rear chamber)corresponding to the guiding hole 4140-1. In some embodiments, theacoustic impedance of the acoustic route (e.g., the front chamber)corresponding to the guiding hole 3940-2 may be different from theacoustic impedance of the acoustic route (e.g., the rear chamber)corresponding to the guiding hole 3940-1, and the acoustic impedance ofthe acoustic route (e.g., the front chamber) corresponding to theguiding hole 4140-2 may be the same as the acoustic impedance of theacoustic route (rear chamber) corresponding to the guiding hole 4140-1.In the embodiment, a ratio of the acoustic impedance (also referred toas an acoustic impedance ratio) of the acoustic route corresponding tothe guiding hole 3940-2 to the acoustic impedance of the acoustic routecorresponding to the guiding hole 3940-1 or a ratio of the acousticimpedance (also referred to as an acoustic impedance ratio) of theacoustic route corresponding to the guiding hole 3940-1 to the acousticimpedance of the acoustic route corresponding to the guiding hole 3940-2may be 0.5-2, 0.6-1.9, 0.7-1.8, 0.8-1.7, 0.8-1.6, 0.8-1.5, 0.8-1.4,0.8-1.3. 0.8-1.2., 0.85-1.15, 0.9-1.1, 0.95-1.05, 0.95-1, etc. In someembodiments, the acoustic impedance of the acoustic routes 3920 and 4120may be adjusted by using an acoustic resistance material (e.g., a tuningnet and/or tuning cotton, etc.) in the acoustic route 3920 and theacoustic route 4120. In some alternative embodiments, the tuning net maybe configured as a waterproof layer, a dust-proof net, etc., for theguiding hole 3940 and the guiding hole 4140. More descriptions regardingthe acoustic impedance may be found elsewhere in the present disclosure.See, e.g., FIGS. 34-36 and the relevant descriptions thereof.

In some embodiments, to further improve the volume of the sound in thelow frequency band, the acoustic driver 3930 may have only one guidinghole 4140, which may be a single point sound source. These changes arewithin the protection scope of the present disclosure.

FIG. 43 is a schematic diagram illustrating guiding holes on a temple ofglasses 3800 according to some embodiments of the present disclosure. Asshown in FIG. 43, a guiding hole 3940-1 and a guiding hole 3940-2corresponding to an acoustic driver 3930 in an acoustic output device3810 may be disposed on a front side of the user's auricle and on thetemple 3830 when the glasses is worn by the user. It should be notedthat the distribution of the guiding hole 3940 and the guiding hole 4140of the acoustic output device 3810 may be not limited to the situationshown in FIGS. 39-43. For example, each or any one of the guiding hole3940-1, the guiding hole 3940-2, the guiding hole 4140-1, and theguiding hole 4140-2 may be disposed at a relatively low side 3831 or anupper side 3834 of the temple 3830. As another example, each or any oneof the guiding hole 3940-1, the guiding hole 3940-2, the guiding hole4140-1, and the guiding hole 4140-2 may be disposed at the inner side3832 or the outer side 3833 of the temple 3830. As yet another example,each or any one of the guiding hole 3940-1, the guiding hole 3940-2, theguiding hole 4140-1, and the guiding hole 4140-2 may be disposed at thefront side of the user's auricle and on any position of the temple 3830when the glasses is worn by the user. As yet another example, each orany one of the guiding hole 3940-1, the guiding hole 3940-2, the guidinghole 4140-1, and the guiding hole 4140-2 may be disposed at a rear sideof the user's auricle on any position of the temple 3830 when theglasses is worn by the user. In some alternative embodiments, each orany one of the guiding hole 3940-1, the guiding hole 3940-2, the guidinghole 4140-1, and the guiding hole 4140-2 may be disposed on the frame3820 or the lens 3840.

In some embodiments, the acoustic output device 3810 may include threeor more acoustic drivers. Each of the three or more acoustic drivers maycorrespond to three or more guiding holes, and each of the three or moreguiding holes may be disposed at any position of the glasses 3800. Thesechanges are within the protection scope of the present disclosure.

In some embodiments, the acoustic output device may perform a soundcollection function. In some embodiments, the acoustic output device mayimprove the sound collection performance of the acoustic output devicethrough a microphone noise reduction system. In some embodiments of thepresent disclosure, glasses with a sound output function and amicrophone noise reduction system may be described as an example. Itshould be understood that the glasses can be considered as a deviceincluding an acoustic output device (e.g., an acoustic output device100, an acoustic output device 300, an acoustic output device 400, anacoustic output device 500, an acoustic output device 600, etc.) and amicrophone noise reduction system (e.g., a microphone noise reductionsystem 4400, a microphone noise reduction system 4500A, or a microphonenoise reduction system 4500B), or the glasses may be used as an acousticoutput device that includes a microphone noise reduction system, whichmay be not limited in the present disclosure.

FIG. 44 is a schematic diagram illustrating a microphone noise reductionsystem according to some embodiments of the present disclosure. Themicrophone noise reduction system 4400 may be configured to reduce oreliminate noises that is not required during microphone soundcollection. In some embodiments, the noises may include a backgroundsound existing when a user wears the audio device or a sound (e.g., atraffic noise, a wind noise, a water noise, an external voice, etc.)that are not needed to be collected. The microphone noise reductionsystem 4400 may be applied to various fields and/or devices, forexample, a headset, a smart device (e.g., a VR glasses, a glasses), amuffler, an anti-snoring device, or the like, or any combinationthereof. In some embodiments, the microphone noise reduction system 4400may be an active noise reduction system configured to reduce the noisesin voice by generating a noise reduction signal (e.g., a signal having aphase opposite to that of the noises). In some embodiments, themicrophone noise reduction system 4400 may be a passive noise reductionsystem configured to reduce the noise by performing a difference onvoice signals collected by two microphone arrays at different positions.

As shown in FIG. 44, the microphone noise reduction system 4400 mayinclude a microphone array 4410, a noise reduction device 4420, and asynthesis device 4430. In some embodiments, two or more components ofthe microphone noise reduction system 4400 may be connected with and/orcommunicated with each other. For example, the noise reduction device4420 may be electrically and/or wirelessly connected with eachmicrophone in the microphone array 4410. As used herein, the connectionbetween two components may include a wireless connection, a wiredconnection, or any other communication connection that can be used fordata transmission and/or data collection. The wireless connection mayinclude a Bluetooth link, a Wi-Fi link, a WiMax link, a WLAN link, aZigbee link, a mobile network link (e.g., 3G, 4G, 5G, etc.), or thelike, or a combination thereof. The wired connection may include acoaxial cable connection, a communication cable (e.g., communicationcable) connection, a flexible cable connection, a spiral cableconnection, a non-metal sheathed cable connection, a metal sheathedcable connection, a multi-core cable connection, a twisted pair cableconnection, a ribbon cable connection, a shielded cable connection, atwin-strand cable connection, an optical fiber connection, a cableconnection, an optical cable connection, a telephone line connection, orthe like, or any combination thereof.

The microphone array 4410 may include at least one low-frequencymicrophone and at least one high-frequency microphone. The at least onelow-frequency microphone may be configured to collect a low-frequencyvoice signal. The at least one high-frequency microphone may beconfigured to collect a high-frequency voice signal. In someembodiments, the at least one low-frequency microphone and the at leastone high-frequency microphone may be integrated into one device. Forexample, at least one low-frequency microphone and/or the at least onehigh-frequency microphone may be integrated and disposed as a microphonedevice in a form of a straight line, a ring, etc., to form a centralizedmicrophone array. In some embodiments, the at least one low-frequencymicrophone and/or the at least one high-frequency microphone may bedistributed in an audio device to form a distributed microphone array.For example, the at least one low-frequency microphone and/or the atleast one high-frequency microphone may be disposed at any position ofthe audio device, and the microphones on the audio device may beconnected wirelessly.

In some embodiments, each microphone in the microphone array 4410 may beconfigured to detect a voice signal (e.g., a voice signal including atarget voice and noise), and process the detected voice signal into atleast two sub-band voice signals. In some embodiments, each microphonein the microphone array 4410 may correspond to a filter, and the voicesignal may be processed to generate at least two sub-band voice signalsthrough the filter. As used herein, the voice signal may be an audiosignal having a specific frequency band. The generated sub-band voicesignals may have a narrower frequency band than a frequency band of thevoice signal, and the frequency bands of the sub-band voice signals maybe within the frequency band of the voice signal. For example, the voicesignal may have a frequency band in a range from 10 Hz to 30 kHz. Thefrequency band of a sub-band voice signal may be 100 Hz to 200 Hz, whichmay be narrower than the frequency band of the voice signal and withinthe frequency band of the voice signal. In some embodiments, acombination of the frequency bands of the sub-band voice signals maycover the frequency band of the voice signal. Additionally oralternatively, at least two of the sub-band voice signals may havedifferent frequency bands. In some embodiments, each of the sub-bandvoice signals may have a characteristic frequency band different fromthat of other sub-band voice signals. Different sub-band voice signalsmay have the same frequency bandwidth or different frequency bandwidths.In the sub-band voice signals, two sub-band voice signals whose centerfrequencies are adjacent to each other may be considered to be adjacentto each other in a frequency domain. More descriptions regarding thefrequency bands of a pair of adjacent sub-band voice signals may befound elsewhere in the present disclosure. See, e.g., FIGS. 46 A and46B, and the relevant descriptions thereof.

In some embodiments, the signal generated by the microphone array 4410may include a digital signal, an analog signal, or the like, or anycombination thereof. In some embodiments, each microphone in themicrophone array 4410 may be a MEMS (Micro Electro Mechanical System)microphone which may have a low operating current, relatively stableperformance, and high voice quality. In some embodiments, some or all ofthe microphones in the microphone array 4410 may be other types ofmicrophones, which may be not limited here.

The noise reduction device 4420 may be configured to perform noisereduction processing on the sub-band voice signals collected by themicrophone array 4410. In some embodiments, the noise reduction device4420 may perform noise estimation, adaptive filtering, voiceenhancement, etc., on the collected sub-band voice signals, so as torealize voice noise reduction. Specifically, the noise reduction device4420 may generate the sub-band noise signals according to a noiseestimation algorithm, generate a sub-band noise correction signalaccording to the sub-band noise signal and generate a target sub-bandvoice signal based on the sub-band voice signals and the sub-band noisecorrection signal, thereby reducing the noise in the sub-band voicesignal. The sub-band noise correction signal may include an analogsignal, a digital signal, etc., which may have a phase opposite to thatof the sub-band noise signal. In some embodiments, the noise estimationalgorithm may include a time recursive average noise estimationalgorithm, a minimum tracking noise estimation algorithm, or the like,or any combination thereof. In some embodiments, the microphone array4410 may include at least one pair of low-frequency microphones and atleast one pair of high-frequency microphones. Each pair of thelow-frequency microphones and/or the high-frequency microphones maycorrespond to sub-band voice signals in the same frequency band. Thenoise reduction device 4420 may regard a voice signal collected by amicrophone of each pair of microphones, which is close to a main soundsource (e.g., a human mouth), as a sub-band voice signal, and regard avoice signal collected by another microphone of the pair of microphones,which is far from the main sound source, as a sub-band noise signal. Thenoise reduction device 4420 may reduce the noise of the sub-band voicesignal by performing a difference operation on the sub-band voice signaland the sub-band noise signal. More descriptions regarding the noisereduction device 4420 and sub-band noise signals may be found elsewherein the present disclosure. See, e.g., FIG. 45A, FIG. 47, and FIG. 48,and the relevant descriptions thereof.

The synthesis device 4430 may be configured to combine the targetsub-band voice signals to generate a target signal. The synthesis device4430 may include any component which can combine the at least twosignals. For example, the synthesis device 4430 may generate a mixedsignal (i.e., the target signal) according to a signal combinationtechnique such as a frequency division multiplexing technique.

In some embodiments, the microphone noise reduction system 4400 mayinclude one or more additional components. One or more components of themicrophone noise reduction system 4400 described above may be omitted.Merely by way of example, a residual noise reduction device may be addedto the noise reduction device 4420. In some embodiments, two or morecomponents of the microphone noise reduction system 4400 may beintegrated into a single component. Merely by way of example, in themicrophone noise reduction system 4400, the synthesis device 4430 may beintegrated into the noise reduction device 4420. These changes are stillin the scope of the present disclosure.

FIG. 45A is a schematic diagram illustrating an exemplary microphonenoise reduction system 4500A according to some embodiments of thepresent disclosure. As shown in FIG. 45A, the microphone noise reductionsystem 4500A may include a microphone array 4510 a, a noise reductiondevice 4520 a, and a synthesis device 4530 a. The microphone array 4510a may include at least two microphones (e.g., a microphone 4512 a-1, amicrophone 4512 a-2, . . . , a microphone 4512 a-n). The count of themicrophones 4512 may be equal to the count of sub-band voice signals.The count of sub-band voice signals (i.e., n) may be related to afrequency band of a voice signal S and frequency bands of generatedsub-band voice signals. For example, a certain count of the microphones4512 may be used, and the combination of the frequency bands of thesub-band voice signals may cover the frequency band of the voice signal.In some embodiments, the frequency bands of any pair of adjacentsub-band voice signals in the sub-band voice signals may be notoverlapped.

The microphones 4512 may have different frequency responses to the voicesignal S and may be configured to generate the sub-band voice signals byprocessing the voice signal S. For example, when a microphone 4512 a-1responds to a voice signal with a frequency of 20 Hz to 3 kHz, afull-band voice signal S (e.g., with a frequency from 2 Hz to 30 kHz)may be processed by the microphone 4512 a-1 to generate a sub-band voicesignal, and the frequency band range of the sub-band voice signal may be20 Hz-3 kHz. In some embodiments, the sub-band voice signals generatedby the microphone array 4510 a may include a digital signal, an analogsignal, or the like, or any combination thereof.

In some embodiments, at least one of the microphones 4512 may include anacoustic channel element and a sound sensitive element. The acousticchannel element may form a route through which the voice signal S (e.g.,the target voice signal, a noise signal) may be transmitted to the soundsensitive element. For example, the acoustic channel element may includeone or more chambers, one or more tubes, or the like, or any combinationthereof. The sound sensitive element may convert the voice signal Stransmitted from the acoustic channel element (e.g., an original voice,a voice processed by the acoustic channel element) into an electricalsignal. For example, the sound sensitive element may include adiaphragm, a board, a cantilever, etc. The diaphragm may be configuredto convert a sound pressure change caused by the voice signal on asurface of the diaphragm into mechanical vibration of the diaphragm. Thesound sensitive element may be made of one or more materials, such asplastic, metal, piezoelectric material, or the like, or any combinationthereof.

In some embodiments, the frequency response of at least one of themicrophones 4512 may be associated with an acoustic structure of theacoustic channel element of the at least one of the microphones 4512.For example, the acoustic channel element of the microphone 4512 a-1 mayhave a specific acoustic structure that may process the sound before thesound reaches the sound sensitive element of the microphone 4512 a-1. Insome embodiments, the acoustic structure of the acoustic channel elementmay have a specific acoustic impedance, thus the acoustic channelelement may be used as a filter for filtering voice and generatesub-band voice signals. The sound sensitive element of the microphone4512 may convert the sub-band voice signals into a sub-band voiceelectrical signal.

In some embodiments, the acoustic impedance of an acoustic structure maybe disposed according to the frequency band of a voice. In someembodiments, an acoustic structure mainly including a chamber may beconfigured as a high-pass filter, and an acoustic structure mainlyincluding a tube may be configured as a low-pass filter. Merely by wayof example, an acoustic channel element may have a chamber and tubestructure. The chamber and tube structure may be a combination of soundcapacity and acoustic quality in series and may form aninductor-capacitor (LC) resonance circuit. When an acoustic resistancematerial is used in the chamber, a resistor-inductor-capacitor (RLC)series loop may be formed, and the acoustic impedance of the RLC seriesloop may be represented by Equation (5) below:

$\begin{matrix}{{Z = {R_{a} + {j\left( {{\omega M_{a}} - \frac{1}{\omega C_{a}}} \right)}}},} & (5)\end{matrix}$where Z represents the acoustic impedance, ω represents an angularfrequency of the chamber and tube structure, j represents a unitimaginary number, M_(a) represents acoustic quality, C_(a) representssound capacity, and R_(a) represents an acoustic resistance of the RLCseries loop. The chamber and tube structure may be used as a band-passfilter (also referred to as a band-pass filter F1). A bandwidth of theband-pass filter F1 may be adjusted by adjusting the acoustic resistanceR_(a). A center frequency of the band-pass filter F1 may be adjusted byadjusting the acoustic quality M_(a) and/or the sound capacity C_(a).For example, the center frequency of the band-pass filter F1 may berepresented by Equation (6) below:ω₀=√{square root over (M _(a) C _(a),)}  (6)

In some embodiments, the frequency response of at least one ofmicrophones 4512 a may be associated with one or more physicalcharacteristics (e.g., material, structure) of a sound sensitive elementof the microphone. The sound sensitive element with specific physicalcharacteristics may be sensitive to a certain frequency band of anaudio. For example, mechanical vibration of one or more elements of asound sensitive element may cause a change of electrical parameters ofthe sound sensitive element. The sound sensitive element may besensitive to a certain frequency band of a voice signal. The frequencyband of the voice signal may cause corresponding changes of theelectrical parameters of the sound sensitive element. In other words, atleast one of the microphones 4512 may be used as a filter for processinga sub-band signal of the voice signal S. In some embodiments, the voicemay be sent to a sound sensitive element through an acoustic channelelement without (or substantially not) being filtered by the acousticchannel element. The physical characteristics of the sound sensitiveelement may be adjusted, and the sound sensitive element may be used asa filter for filtering the voice and converting the filtered voice intoone or more sub-band voice electrical signals.

Merely by way of example, the sound sensitive element may include adiaphragm, which may be configured as a band-pass filter (also referredto as a band-pass filter F2). A center frequency of the band-pass filterF2 may be represented by Equation (7) as below:

$\begin{matrix}{{\omega_{0}^{\prime} = \sqrt{\frac{K_{m}}{M_{m}}}},} & (7)\end{matrix}$where M_(m) represents to the mass of the diaphragm, and K_(m)represents an elasticity coefficient of the diaphragm. In someembodiments, a bandwidth of the band-pass filter F2 may be adjusted byadjusting the damping (R_(m)) of the diaphragm. The center frequency ofthe band-pass filter F2 may be adjusted by adjusting the mass of thediaphragm M_(m) and/or the elasticity coefficient of the diaphragmK_(m).

As described above, the acoustic channel element or the sound sensitiveelement of at least one of the microphones 4512 may be used as a filter.The frequency response of the at least one of microphones 4512 may beadjusted by adjusting the parameters (e.g., R_(a), M_(a) and/or C_(a))of the acoustic channel element or the parameters (e.g., K_(m) and/orR_(m)) of the sound sensitive element. In some embodiments, thecombination of the acoustic channel element and the sound sensitiveelement may be used as a filter. By adjusting the parameters of theacoustic channel element and the sound sensitive element, the frequencyresponse of the combination of the acoustic channel element and thesound sensitive element may be adjusted accordingly. More descriptionsregarding the acoustic channel element and/or the sound sensitiveelement used as a band-pass filter may be found in, for example,International Application No. PCT/CN2018105161, filed on Sep. 12, 2018,the entire contents of which are hereby incorporated by reference.

The noise reduction device 4520 a may include at least two sub-bandnoise reduction units 4522 (e.g., a sub-band noise reduction unit 4522a-1, a sub-band noise reduction unit 4522 a-2, . . . , a sub-band noisereduction unit 4522 a-n). Each of the sub-band noise reduction units4522 may correspond to one of the microphones 4512. The at least twosub-band noise reduction units 4522 a may be configured to generatesub-band noise correction signals based on noises in a sub-band voicesignal, reduce noises in the sub-band voice signal, and generate atarget sub-band voice signal. For example, a sub-band noise reductionunit 4522 a-i (i and n are any integer greater than 1 and i is equal toor less than n) may receive a sub-band voice signal Si from a microphone4512 a-i, and generate a sub-band noise correction signal Ci, therebyreducing the noise of the sub-band voice signal Si. In some embodiments,at least one of the at least two sub-band noise reduction units 4522 amay include a sub-band noise estimation sub-unit (not shown in FIG. 45A)and a sub-band noise suppression sub-unit (not shown in FIG. 45A). Thesub-band noise estimation sub-unit may be configured to estimate thenoise in the sub-band voice signal. The sub-band noise suppressionsub-unit may be configured to receive the noise in the sub-band voicesignal from the sub-band noise estimation sub-unit and generate asub-band noise correction signal, thereby reducing the sub-band noisesignal in the sub-band voice signal.

In some embodiments, a sub-band voice signal may be sent from one of themicrophones 4512 to one of the at least two sub-band noise reductionunits 4522 a through a parallel transmitter. In some embodiments, thesub-band voice signal may be transmitted via the parallel transmitteraccording to a specific communication protocol for transmitting adigital signal. An exemplary communication protocol may include AudioEngineering Society (AES3), European Broadcasting Union (AES/EBU),European Broadcasting Union (EBU), Automatic Data Accumulator andPropagation (ADAT), Inter-IC Sound (I2S), Time-division Multiplexing(TDM), Musical Instrument Digital Interface (MIDI), CobraNet, EthernetAudio/Video Patch Cord (Ethernet AVB), Dante, InternationalTelecommunication Union (ITU)-T G. 728, ITU-T G. 711, ITU-T G. 722,ITU-T G. 722.1, ITU-T G. 722.1 Advanced Audio Coding (Annex C, AAC)-LD,or the like, or any combination thereof. The digital signal may betransmitted via various manners, such as Compact Disc (CD), WAVE, AudioInterchange File Format (AIFF), Moving Picture Experts Group (MPEG)-1,MPEG-2, MPEG-3, MPEG-4, Musical Instrument Digital Interface (MIDI),Windows Media Audio (WMA), RealAudio, Transform-domain WeightedNterleave Vector Quantization (VQF), Adaptive Multi-rate (AMR), APE,Free Lossless Audio Codec (FLAC), Advanced Audio Coding (AAC), or thelike, or any combination thereof. In some embodiments, a sub-band voicesignal may be processed into a single-channel signal using, for example,a frequency division multiplexing technique, and the single-channelsignal may be transmitted to at least one of the at least two sub-bandnoise reduction units 4522 a.

In some embodiments, the sub-band noise reduction unit 4522 a-i mayestimate a sub-band noise signal N_(i), and perform phase modulationand/or amplitude modulation on the sub-band noise signal N_(i) togenerate a sub-band noise correction signal N_(i)′. In some embodiments,the phase modulation and the amplitude modulation may be sequentially orsimultaneously performed on the sub-band noise signal N_(i). Forexample, the sub-band noise reduction unit 4522 a-i may perform thephase modulation on the sub-band noise signal N_(i) to generate a phasemodulation signal, and perform the amplitude modulation on the phasemodulation signal to generate the sub-band noise correction signalN_(i)′. The phase modulation of the sub-band noise signal N_(i) mayinclude inversion of the phase of the sub-band noise signal N_(i). Insome embodiments, a phase of the noises may shift during propagation ofthe noise from a position of the microphone 4512 a-i to a position ofthe sub-band noise reduction unit 4522 a-i. The phase modulation of thesub-band noise signal N_(i) may also include compensating for the phaseshift of the sub-band noise signal N_(i) during propagation of thesub-band noise signal N_(i). Specifically, the sub-band noise reductionunit 4522 a-i may perform amplitude modulation on the sub-band noisesignal N_(i) to generate an amplitude modulation signal, and performphase modulation on the amplitude modulation signal to generate thesub-band noise correction signal N_(i)′. More descriptions regarding thesub-band noise reduction unit 4522 a-i may be found elsewhere in thepresent disclosure. See, e.g., FIGS. 47 and 48, and the relevantdescriptions thereof.

In some embodiments, the noise reduction device 4520 a may use two setsof microphones with the same configuration (e.g., two microphone arrays4510 a) to perform noise reduction according to the principle ofdual-microphone noise reduction. Each set of microphones may includemicrophones corresponding to a plurality of sub-band voice signals withdifferent frequency bands. For illustration purposes, one of the twosets of microphones with the same configuration may be referred to as afirst microphone set, and the other set of microphones may be referredto as a second microphone set. A distance between the first microphoneset and a main sound source (e.g., the human mouth) may be closer than adistance between the second microphone set and the main sound source. Asused herein, a distance between a microphone set and the main soundsource refers to a distance between a microphone in the microphone setor a position in an area configured with the microphone set and the mainsound source. For example, the distance between the first microphone setand the main sound source (e.g., the human mouth) may include a distancebetween a center microphone arranged in the first microphone set and themain sound source, and the distance between the second microphone setand the main sound source (e.g., the human mouth) may include a distancebetween a center microphone arranged in the second microphone set andthe main sound source. Each microphone in the first microphone set maycorrespond to a microphone in the second microphone one to one. Forexample, a first microphone in the first microphone set with a frequencyband of 20 Hz-3 kHz may correspond to a second microphone in the secondmicrophone set with a frequency band of 20 Hz-3 kHz. The signalcollected by the first microphone in the first microphone set may beregarded as a sub-band voice signal, and the signal collected by thesecond microphone in the second microphone set may be regarded as asub-band noise signal. The noise reduction device 4520 a may generate atarget sub-band voice signal according to the sub-band voice signal andthe sub-band noise signal. More descriptions regarding performing noisereduction using two microphone arrays may be found elsewhere in thepresent disclosure. See, e.g., FIG. 46A or FIG. 46B and the relevantdescriptions thereof.

The synthesis device 4530 a may be configured to combine one or moretarget sub-band voice signals to generate a target signal S′.

It should be noted that the descriptions of the microphone array 4510 aand/or the noise reduction device 4520 a may be intended to beillustrative, which does not limit the scope of the present disclosure.Various substitutions, modifications, and changes may be obvious tothose skilled in the art. The features, structures, methods, and otherfeatures of the exemplary embodiments described herein may be combinedin various ways to obtain additional and/or alternative exemplaryembodiments. For example, the microphone array 4510 a and/or the noisereduction device 4520 a may include one or more additional components.As another example, one or more components of the microphone array 4510a and/or noise reduction device 4520 a may be omitted. As yet anotherexample, two or more components of the microphone array 4510 a and/orthe noise reduction device 4520 a may be integrated into a singlecomponent.

FIG. 45B is a schematic diagram illustrating an exemplary microphonenoise reduction system according to some embodiments of the presentdisclosure. As shown in FIG. 45B, a microphone noise reduction system4500B may include a microphone array 4510 b, a noise reduction device4520 b, and a synthesis device 4530 b. The microphone array 4510 b mayinclude at least two microphones 4512 (e.g., a microphone 4512 b-1, amicrophone 4512 b-2, . . . , microphone 4512 b-n) and at least twofilters 4514 (e.g., a filter 4514 b-1, a filter 4514 b-2, . . . , afilter 4514 b-n). The count of the microphones 4512, the count offilters 4514, and the count of sub-band voice signals may be equal. Theat least two microphones 4512 may have the same configuration. In otherwords, each of the microphones 4512 may have the same frequency responseto a voice signal S. When a microphone of the microphones 4512 receivesthe voice signal S, the microphone may transmit the voice signal S toone of the filters 4514 corresponding to the microphone, and thesub-band voice signal may be generated through the one of the filters4514. The filters 4514 corresponding to each of the microphones 4512 mayhave different frequency responses to the voice signal S. In someembodiments, at least one of the filters 4514 may include a passivefilter, an active filter, an analog filter, a digital filter, etc., orany combinations thereof.

The noise reduction device 4520 b may include at least two sub-bandnoise reduction units 4522 (e.g., a sub-band noise reduction unit 4522b-1, a sub-band noise reduction unit 4522 b-2, . . . , a sub-band noisereduction unit 4522 b-n). Each of the sub-band noise reduction units4522 may correspond to a filter of the filters 4514 (or a microphone ofthe microphones 4512). More descriptions regarding the noise reductiondevice 4520 b and the synthesis device 4530 b may be found elsewhere inthe present disclosure. See, e.g., FIG. 45A and the relevantdescriptions thereof.

FIG. 46A is a schematic diagram illustrating an exemplary frequencyresponse 4610 of a first microphone and an exemplary frequency response4620 of a second microphone according to some embodiments of the presentdisclosure. FIG. 46B is a schematic diagram illustrating the frequencyresponse 4610 of the first microphone and another exemplary frequencyresponse 4630 of the second microphone according to some embodiments ofthe present disclosure. The first microphone may be configured toprocess a voice signal to generate a first sub-band voice signal. Thesecond microphone may be configured to process a voice signal togenerate a second sub-band voice signal. In sub-band voice signals, thesecond sub-band voice signal may be adjacent to the first sub-band voicesignal in a frequency domain.

In some embodiments, the frequency responses of the first microphone andthe second microphone may have the same frequency bandwidth. Forexample, as shown in FIG. 46A, the frequency response 4610 of the firstmicrophone may have a low half power point f1, a high half power pointf2, and a center frequency f3. As used herein, a half power point of afrequency response refers to a frequency point with a specific powersuppression (e.g., −3 dB). A frequency bandwidth of the frequencyresponse 4610 may be equal to a difference between the high half powerpoint f2 and the low half power point f1. The frequency response 4620 ofthe second microphone may have a low half power point f2, a high halfpower point f4, and a center frequency f5. A frequency bandwidth of thefrequency response 4620 may be equal to a difference between the highhalf power point f4 and the low half power point f2. The frequencybandwidth of the first microphone may be equal to the frequencybandwidth of the second microphone.

In some embodiments, the frequency response of the first microphone andthe frequency response of the second microphone may have differentfrequency bandwidths. For example, as shown in FIG. 46B, the frequencyresponse of the second microphone 4630 may have the low half power pointf2, a high half power point f7 (which is greater than f4), and a centerfrequency f6. The frequency bandwidth of the frequency response 4630 ofthe second microphone may be equal to a difference between the high halfpower point f7 and the low half power point f2 and the differencebetween the high half power point f7 and the low half power point f2(i.e., the frequency bandwidth of the frequency response 4630 of thesecond microphone) may be greater than the frequency bandwidth of thefrequency response 4610 of the first microphone. Accordingly, relativelyfew microphones may be needed in the microphone array 4510 a to generatethe sub-band voice signals to cover the frequency band of an originalvoice signal.

In some embodiments, the frequency response of the first microphone andthe frequency response of the second microphone may intersect at afrequency point. The intersection of the frequency response of the firstmicrophone and the frequency response of the second microphone mayindicate that an overlapping range exists between the first frequencyresponse and second frequency response. On an ideal occasion, thefrequency response of the first microphone and the frequency response ofthe second microphone may have no overlapping range. The frequencyresponse of the first microphone and the frequency response of thesecond microphone having an overlapping range may cause an interferencerange between the first sub-band voice signal and the second sub-bandvoice signal and affect the quality of the first sub-band voice signaland the second sub-band voice signal. For example, the larger theoverlapping range is, the larger the interference range may be, and thelower the quality of the first sub-band voice signal and the secondsub-band voice signal may be.

In some embodiments, the frequency point at which the frequencyresponses of the first microphone and the second microphone intersectmay be close to the half power point of the frequency response of thefirst microphone and/or the half power point of the frequency responseof the second microphone. As shown in FIG. 46A, the frequency response4610 and the frequency response 4620 intersect at the high half powerpoint f2 of the frequency response 4610, which may be the low half powerpoint of the frequency response 4620. It should be noted that when apower level difference between the frequency point and the half powerpoint is not greater than a threshold (e.g., 2 dB), it may be consideredthat the frequency point is close to the half power point. In this case,the frequency response of the first microphone and the frequencyresponse of the second microphone may have relatively little energy lossor repetition, which may result in an overlapping range between thefrequency response of the first microphone and the frequency response ofthe second microphone. Merely by way of example, when the half powerpoint is −3 dB and the threshold is −2 dB, when the frequency responseof the first microphone and the frequency response of the secondmicrophone intersects at a frequency point with a power level greaterthan −5 dB and/or less than −1 dB, the overlapping range may beconsidered to be relatively small. In some embodiments, the centerfrequency and/or the bandwidth of the frequency response of the firstmicrophone and the center frequency and/or the bandwidth of thefrequency response of the second microphone may be adjusted to generatea relatively narrow or an required overlapping range between thefrequency response of the first microphone and that of the secondmicrophone, thereby avoiding the overlapping between the frequency bandof the first sub-band voice signal and that of the second sub-band voicesignal.

It should be noted that the descriptions of the embodiments in FIG. 46Aand FIG. 46B are intended to be illustrative, which does not limit thescope of the present disclosure. Various substitutions, modifications,and changes may be obvious to those skilled in the art. The features,structures, methods, and other features of the exemplary embodimentsdescribed herein may be combined in various ways to obtain additionaland/or alternative exemplary embodiments. For example, one or moreparameters (e.g., the frequency bandwidth, the high half power point,the low half power point, and/or the center frequency) of the frequencyresponse of the first microphone and/or that of the frequency responseof the second microphone may be determined based on actual needs.

FIG. 47 is a schematic diagram illustrating an exemplary sub-band noisesuppression sub-unit 4700 according to some embodiments of the presentdisclosure. The sub-band noise suppression sub-unit 4700 may beconfigured to receive a sub-band noise signal N_(i)(n) from a sub-bandnoise estimation sub-unit and generate a sub-band noise correctionsignal A_(t)N′_(i)(n), thereby modulating a frequency of the sub-bandnoise signal N_(i)(n) and reducing an amplitude of the sub-band noisesignal N_(i)(n). A_(t) refers to an amplitude suppression coefficient,which is related to noises to be reduced.

As shown in FIG. 47, the sub-band noise suppression sub-unit 4700 mayinclude a phase modulator 4710 and an amplitude modulator 4720. Thephase modulator 4710 may be configured to receive the sub-band noisesignal N_(i) (n) and generate a phase modulation signal N′_(i)(n) byinverting the phase of the sub-band noise signal N_(i)(n). For example,as shown in FIG. 48, a phase modulation signal N′_(i)(n) may begenerated by inverting the phase of the sub-band noise signal N_(i)(n).In some embodiments, the phase of the noise may be shifted during thenose is propagated from a position of a microphone (e.g., the microphone4512 a-i) to a position of a sub-band noise reduction unit (e.g., thesub-band noise reduction unit 4522 a-i). In some embodiments, the phaseshift of the noise may be ignored. For example, when the noise ispropagated in a single direction in a form of a plane wave while thenoise is propagated from the position of the microphone to the positionof the sub-band noise reduction unit (or a part thereof), and the phaseshift during the propagation of the noise is less than a threshold, itmay be considered that the phase of the noise is not shifted and may beignored when the phase modulation signal N′_(i)(n) is generated. Whenthe phase shift of the noise is greater than the threshold, it may beconsidered that the phase of the noise is shifted. In some embodiments,when the phase shift of a sub-band noise is negligible, the phasemodulator 4710 may generate the phase modulation signal N′_(i)(n) byperforming phase inversion on the sub-band noise signal N_(i)(n).

In some embodiments, when the phase shift of the sub-band noise is notnegligible, the phase modulator 4710 may consider the phase shift of thesub-band noise when the phase modulator 4710 generates the phasemodulation signal N′_(i)(n). For example, the phase of the sub-bandnoise signal N_(i)(n) may have a phase shift Δφ in a propagationprocess. The phase shift Δφ may be determined according to Equation (8)below:

$\begin{matrix}{{{\Delta\varphi} = {\frac{2\pi f_{0}}{c}\Delta d}},} & (8)\end{matrix}$where f₀ represents the center frequency of the sub-band noise signalN_(i) (n), c represents a speed of the sound. When the noise is anear-field signal, Δd represents a difference between the distance fromthe sound source to the microphone 4512 a-i and the distance from thesound source to the sub-band noise reduction unit 4522 a-i (or a partthereof). When the noise is a far-field signal, Δd may be equal to d cosθ, wherein d represents the distance between the microphone 4512 a-i andthe sub-band noise reduction unit 4522 a-i (or a part thereof), and θrepresents an angle between the sound source and the microphone 4512 a-ior an angle between the sound source and the sub-band noise reductionunit 4522 a-i (or a part thereof).

To compensate for the phase shift Δφ, the phase modulator 4710 mayperform the phase inversion and phase compensation on the sub-band noisesignal N_(i) (n) to generate the phase modulation signal N′_(i)(n). Insome embodiments, the phase modulator 4710 may include an all-passfilter. The function of the all-pass filter may be denoted as |H (w)|,wherein w represents an angular frequency. On an ideal occasion, anamplitude response of the all-pass filter may be equal to 1, and a phaseresponse of the all-pass filter may be equal to the phase shift Δφ. Theall-pass filter may delay the sub-band noise signal N_(i)(n) by ΔT toperform the phase compensation. In some embodiments, ΔT may bedetermined according to Equation (9) below:

$\begin{matrix}{{{\Delta T} = {\frac{\Delta\varphi}{2\pi f_{0}} = \frac{\Delta d}{c}}},} & (9)\end{matrix}$

In this case, the phase modulator 4710 may perform the phase inversionand the phase compensation on the sub-band noise signal N_(i) (n) togenerate the phase modulation signal N′_(i)(n).

The amplitude modulator 4720 may be configured to receive the phasemodulation signal N′_(i)(n) and generate a target modulation signalA_(t)N′_(i)(n) by modulating the phase modulation signal N′_(i)(n). Insome embodiments, the noise may be suppressed during the propagation ofthe noise from the position of the microphone 4512 a-i to the positionof the sub-band noise reduction unit 4522 a-i (or a part thereof). Theamplitude suppression coefficient A_(t) may be determined to measure theamplitude suppression of the noise during propagation. The amplitudesuppression coefficient A_(t) may be associated with one or morefactors, including: for example, the material and/or structure of anacoustic channel element for sound transmission, the position of themicrophone 4512 a-i relative to the sub-band noise reduction unit 4522a-i (or a part thereof), or the like, or any combination thereof.

In some embodiments, the amplitude suppression coefficient A_(t) may bea default of the microphone noise reduction system 4400 as shown in FIG.44, or may be predetermined based on an actual or simulated experiment.For example, the amplitude suppression coefficient A_(t) may bedetermined by comparing an amplitude of an audio signal near themicrophone 4512 a-i (e.g., before the audio signal entering an audiobroadcasting device) with the amplitude after the audio signal istransmitted to the position of the sub-band noise reduction unit 4522a-i. In some embodiments, the amplitude suppression of the noise may beignored. For example, when the amplitude suppression during propagationof the noise is less than a threshold and/or the amplitude suppressioncoefficient A_(t) may be equal to (or substantially equal to) 1, thephase m N′_(i)(n) may be designated as the sub-band noise correctionsignal (i.e., the target modulation signal A_(t)N′_(i)(n) of thesub-band noise signal N_(i)(n).

In some embodiments, the sub-band noise suppression sub-unit 4700 mayinclude a sub-band voice signal generator (not shown in FIG. 47). Thesub-band voice signal generator may generate a target sub-band voicesignal C_(i)(n) according to the sub-band noise correction signalA_(t)N′_(i)(n) and a sub-band voice signal S_(i) (n), and transmit thetarget sub-band voice signal to the synthesis device 4430 as shown inFIG. 44. The synthesis device 4430 may combine at least two targetsub-band voice signals into one target signal S(n) according to Equation(10) below:S(n)=Σ_(i=1) ^(m) C _(i)(n),  (10)

It should be noted that the descriptions of the embodiments in FIGS. 47and 48 and FIG. 46B may be intended to be illustrative, which does notlimit the scope of the present disclosure. Various substitutions,modifications, and changes may be obvious to those skilled in the art.The features, structures, methods, and other features of the exemplaryembodiments described herein may be combined in various ways to obtainadditional and/or alternative exemplary embodiments. For example, thesub-band noise suppression sub-unit 4700 may include one or moreadditional components, such as a signal synthesis unit. As anotherexample, one or more components in the sub-band noise suppressionsub-unit 4700, such as the amplitude modulator 4720, may be omitted.

FIGS. 49A and 49B are schematic diagrams illustrating exemplary glasses4900 according to some embodiments of the present disclosure. Theglasses 4900 may include a frame 4910, one or more temples 4920 (e.g., atemple 4920-1 and a temple 4920-2), and one or more lenses 4930 (e.g., alens 4930-1 and a lens 4930-2). The frame 4910 and the temples 4920 maybe called a glasses support together. The frame 4910 may be configuredto support the lens 4930. A bridge 4912 may be disposed in the middle ofthe frame 4910. The bridge 4912 may be placed on the bridge of the noseof a user when the user wears the glasses 4900. The temples 4920 may beplaced on the user's ears when the user wears the glasses 4900. Thetemples 4920 may cooperate with the bridge 4912 to support the frame4910. In some embodiments, the frame 4910 and the temples 4920 may beconnected via a connection unit 4940, and the temples 4920 may befolded. In some embodiments, the frame 4910 may be detachably connectedto the temples 4920. The connection unit 4940 may include a snapconnection unit, a plug connection unit, a hinge connection unit, or thelike, or any combination thereof. In some embodiments, the frame 4910and the temples 4920 may not be connected via the connection unit 4940.In other words, the glasses support (e.g., the frame 4910 and thetemples 4920) may be integrally formed.

A type of the lenses 4930 may be various, which may be not limitedherein. For example, the lenses 4930 may be the same as or similar tothe lenses 3840 in FIG. 38.

At least one of the temples 4920 (e.g., the temple 4920-2) may include afront end 4922 connected with the frame 4910 and a rear end away fromthe frame 4910. A hook-shaped structure a first end of which may beintegrally formed with the front end 4922, a second end 4924 of thehook-shaped structure away from the frame 4910 may be bent downward. Thehook-shaped structure may be hooked on a rear end 4924 of the user's earwhen the user wears the glasses 4900. In some embodiments, to savematerial of the glasses 4900 and improve wearing comfort of the user, asectional area of the second end 4924 may be smaller than a sectionalarea of the first end 4922, that is, the second end 4924 may be thinnerthan the first end 4922. In some embodiments, an immobilization unit(e.g., an immobilization unit 5260 in FIG. 52A) may be disposed in acenter of at least one of the temples 4920. The immobilization unit maybe configured to immobilize the glasses 4900 on the user's ears and maybe not easy to loosen.

In some embodiments, the temples 4920 and/or the frame 4910 may be madeof metal material (e.g., copper, aluminum, titanium, gold, etc.), alloymaterial (e.g., aluminum alloys, titanium alloys, etc.), plasticmaterial (e.g., polyethylene, polypropylene, epoxy resin, nylon, etc.),fiber material (e.g., acetate fiber, propionic acid fiber, carbon fiber,etc.), or the like, or any combination thereof. The material of theframe 4910 and that of the temples 4920 may be the same or different.For example, the frame 4910 may be made of plastic material, and thetemples 4920 may be made of metal material. As another example, theframe 4910 may be made of plastic material, and the temples 4920 may bemade of metal and plastic material. In some embodiments, a protectivecover may be disposed on the temple 4920-1 and/or the temple 4920-2. Theprotective cover may be made of soft material with certain elasticity,such as soft silica gel, rubber, etc., to provide a soft touch sense forthe user.

In some embodiments, as shown in FIG. 48B, a vertical distance h1between a symmetry center of the frame 4910 and a center point of a lineconnecting a second end of the temple 4920-1 and a second end of thetemple 4420-2 may be 8 centimeters-0 centimeters. In some embodiments,the vertical distance h1 may be 8.5 centimeters-19 centimeters, 9centimeters-18 centimeters, 9.5 centimeters-17 centimeters, 10centimeters 16 centimeters, 10.5 cm-15 cm, 11 centimeters-14centimeters, 11.5 centimeters-13 centimeters, etc. As shown in FIG. 48B,a distance h2 between center points of the connection unitscorresponding to the temple 4920-1 and the temple 4920-2 may be 7centimeters-17 centimeters, 7.5 centimeters-16 centimeters, 8centimeters-15 centimeters, 8.5 centimeters-14 centimeters, 9centimeters-13 centimeters, 9.5 centimeters-12 centimeters, 10centimeters-11 centimeters, etc.

The glasses support (e.g., the frame 4910 and/or the temples 4920) mayinclude a hollow structure. An acoustic output device (e.g., theacoustic output device 100, the acoustic output device 300, the acousticoutput device 400, the acoustic output device 500, the acoustic outputdevice 600, etc.), a microphone noise reduction system (e.g., themicrophone noise reduction system 4400, the microphone noise reductionsystem 4500A, the microphone noise reduction system 4500B, etc.), acircuit board, a battery slot, etc., may be disposed in the hollowstructure.

The acoustic output device may be configured to output sound to theuser. In some embodiments, the acoustic output device may include atleast one set of low-frequency acoustic drivers and at least one set ofhigh-frequency acoustic drivers. In some embodiments, when a distancebetween guiding holes corresponding to the high-frequency acousticdrivers is smaller than a distance between guiding holes correspondingto the low-frequency acoustic drivers, a sound volume heard by theuser's ears may be increased, and a small sound leakage may begenerated, thereby preventing the sound from being heard by others nearthe user of the acoustic output device. In some embodiments, theacoustic output device may include at least one set of acoustic drivers.For example, as shown in FIG. 52A, the at least one set of acousticdrivers may include an acoustic driver 5240 and an acoustic driver 5250.A temple 5200A may include a sound hole 5245 and a sound hole 5255 thatcooperate with the acoustic driver 5240 and the acoustic driver 5250,respectively. The acoustic driver 5250 and the sound hole 5255 may bedisposed at a rear end 5224 of the temple 5200A. The sound hole 5245 andthe sound hole 5255 may be (or approximately be) regarded as two-pointsound sources (i.e., a dual-point sound source). Generally, a baffledisposed between the dual-point sound source may increase the volume ofthe near-field sound and not significantly increase the volume of thefar-field leakage, thereby improving the user's hearing experience. Whenthe glasses 4900 equipped with the temple 5200A is worn by the user, thesound hole 5245 may be on a front side of an ear, and the sound hole5255 may be on a rear side of the ear. The auricle of the user may beregarded as the baffle between the sound hole 5245 and the sound hole5255. The auricle may increase a distance between the sound hole 5245and the sound hole 5255. When the glasses are playing voice, the bafflemay significantly increase the volume of the near-field sound, therebyimproving the user's hearing experience. More descriptions regarding theacoustic output device may be found elsewhere in the present disclosure.See, e.g., FIG. 1 to FIG. 37 and the relevant descriptions thereof.

The microphone noise reduction system may include a microphone array, anoise reduction device, a synthesis device, etc. Each microphone of themicrophone array may be configured to collect sub-band voice signals.The noise reduction device may be configured to generate a phasemodulation signal with a phase opposite to one of the sub-band noisesignal according to the sub-band noise signals in the collected sub-bandvoice signals, thereby reducing the noise of the sub-band voice signal.Denoised sub-band voice signals corresponding to the collected sub-bandvoice signals may be transmitted to the synthesis device to besynthesized to generate a target voice signal. More descriptionsregarding the microphone noise reduction system may be found elsewherein the present disclosure. See, e.g., FIG. 44, FIG. 45A, and/or FIG.45B, and the relevant descriptions thereof. In some embodiments, themicrophone array may be disposed on at least one of the temples 4920 orthe frame 4910. More descriptions regarding the disposition of themicrophone array may be found elsewhere in the present disclosure. See,e.g., FIG. 50 A, FIG. 50 B, FIG. 51 A, and FIG. 51 B, and the relevantdescriptions thereof. In some embodiments, the positions of the noisereduction device and the synthesis device in the glasses 4900 may bedisposed according to actual needs, which are not limited herein. Forexample, the noise reduction device and the synthesis device may beintegrated together on the circuit board. As another example, the noisereduction device and the synthesis device may be disposed on at leastone of the temples 4920 or the frame 4910, respectively. In someembodiments, a Bluetooth unit may be integrated into the circuit board.The battery slot may be configured to install the battery which may beconfigured to provide power to the circuit board. Through the integratedBluetooth unit, the glasses 4900 may realize a function such as makingand/or answering a call, listening to music, etc.

FIG. 50A and FIG. 50B are schematic diagrams of exemplary templesaccording to some embodiments of the present disclosure. As shown inFIGS. 50A and 50B, one of the temples 4920 (e.g., the temple 4920-1and/or the temple 4920-2) may be a hollow structure. The hollowstructure may be configured to accommodate a microphone array 5010(e.g., the microphone array 4410 in the microphone noise reductionsystem 4400), a circuit board 5020, a battery slot 5030, and an acousticoutput device 5040. In some embodiments, the hollow structure mayinclude a noise reduction device and a synthesis device (not shownherein). As shown in FIG. 50B, a sound inlet 5015 (or a sound hole forinputting the sound) matched with the microphone array 5010, and a soundoutlet 5045 (or a sound hole for outputting the sound) matched with theacoustic output device 5040 may be disposed on a surface of one of thetemples 4920. It should be indicated out that positions of themicrophone array 5010, the circuit board 5020, the battery slot 5030,the acoustic driver 5040, and other components may be adjusted in thehollow structure according to actual needs, which may be not the same asillustrated in FIG. 50A. For example, the position of the battery slot5030 and the position of the circuit board 5020 may be exchanged. Asanother example, the microphone array 5010 may be disposed at a rear end5024 of the one of temples 4920. In some embodiments, the microphonearray may be disposed in the frame 4910 (e.g., the bridge 4912).

FIG. 51A and FIG. 51B are schematic diagrams of the exemplary glasses4900 according to some embodiments of the present disclosure. As shownin FIGS. 51A and 51B, a microphone array 5110 may be disposed at thebridge 4912 in a middle of the frame 4910. A sound inlet 5115 may bedisposed on a surface of the bridge 4912, which may be matched with themicrophone array 5110.

In some embodiments, when a user wears the glasses 4900, a distance Dbetween a center point of the microphone array 5010 as shown in FIG. 50Aor the microphone array 5110 and a center point of the user's mouth(i.e., a main sound source) may be 2 centimeters-20 centimeters (e.g.,FIG. 51A). In some embodiments, the distance D may be 2.5 centimeters-18centimeters, 3 centimeters-16 centimeters, 3.5 centimeters-14centimeters, 4 centimeters-12 centimeters, 4.5 centimeters-10centimeters, 5 centimeters-8 centimeters, 5.5 centimeters-7.5centimeters, 6 centimeters-7 centimeters, etc.

In some embodiments, the microphone array 5010 may include at least apair of low-frequency microphones and at least a pair of high-frequencymicrophones. The configuration of each pair of microphones may be thesame. That is, the configurations of low-frequency microphones in onepair may be the same; the configurations of high-frequency microphonesin one pair may be the same. Each pair of microphones may correspond tosub-band voice signals with the same frequency band. That is, thesub-band voice signals corresponding to low-frequency microphones in onepair may have the same frequency band; the sub-band voice signalscorresponding to high-frequency microphones in one pair may have thesame frequency band. A distance between microphones in each pair ofmicrophones may be the same. That is, a distance between microphones ofeach pair of low-frequency microphones may be equal to a distancebetween microphones of each pair of high-frequency microphones. Forillustration purposes, a microphone of each pair of microphones closerto the main sound source may be regarded as a first microphone, and amicrophone of each pair of microphones away from the main sound sourcemay be regarded as a second microphone. FIG. 52A is a schematic diagramillustrating an exemplary temple 5200 of glasses according to someembodiments of the present disclosure. As shown in FIG. 52A, a hollowstructure of the temple 5200A may include two sets of microphones thatcorrespond to each other. That is, a microphone array may include twomicrophone sets (e.g., a first microphone set 5212 and a secondmicrophone set 5214), and the two microphone sets may correspond to eachother. Each of the first microphone set 5212 and the second microphoneset 5214 may include microphones corresponding to a plurality ofsub-band voice signals with different frequency bands. A microphone inthe first microphone set 5212 may correspond to a microphone in thesecond microphone set 5214 one to one. A microphone in the firstmicrophone set 5212 and a corresponding microphone in the secondmicrophone set 5214 may correspond to sub-band voice signals with thesame frequency band. For example, each microphone in the firstmicrophone set 5212 and/or the second microphone set 5214 may decomposea voice signal into a sub-band voice signal. The voice signal may beprocessed by a first microphone in the first microphone set 5212 and acorresponding second microphone in the second microphone set 5214, andsub-band voice signals with the same frequency band may be generated bythe first microphone and the corresponding second microphone.

A distance between the first microphone set 5212 and the main soundsource (e.g., a human mouth) may be less than a distance between thesecond microphone set 5214 and the main sound source. In someembodiments, the first microphone set 5212 and the second microphone set5214 may be distributed in the temple 5200A in a specific manner, andthe main sound source may be in a direction from the second microphoneset 5214 pointing to the first microphone set 5214.

In some embodiments, for a first microphone 5212-i and a secondmicrophone 5214-i corresponding to the first microphone 5212-i, due tothe distance between the main sound source and the first microphone5212-i and/or the distance between the main sound source and the secondmicrophone 5214-i may be smaller than distances between other soundsources (e.g., a noise source) in the environment and the firstmicrophone 5212-i and/or distances between the other sound sources andthe second microphone 5214-i when the user wears the glasses with thetemple 5200A, the main sound source may be regarded as a near-fieldsound source of the first microphone 5212-i and the second microphone5214-i. For the near-field sound source, a volume of a sound received bya microphone may be associated with the distance between the near-fieldsound source and the microphone. The first microphone 5212-i may beclose to the main sound source than the second microphone 5214-i, and anaudio signal may be processed by the first microphone 5212-i to generatea relatively great sub-band voice signal V_(J1). The second microphone5214-i may be relatively far away from the main sound source than thefirst microphone 5212-i, and the audio signal may be processed by thesecond microphone 5214-i to generate a relatively small sub-band voicesignal V_(J2), and V_(J1) is greater than the V_(J2). As used herein, afirst signal greater than a second signal refers to that the amplitude(i.e., the intensity) of the first signal exceeds the amplitude (i.e.,the intensity) of the second signal.

In some embodiments, the noise source in the environment may berelatively far away from the first microphone 5212-i and the secondmicrophone 5214-i, and the noise source may be regarded as a far-fieldsound source of the first microphone 5212-i and the second microphone5214-i. For the far-field sound source, the noise is processed by themicrophone sets and used to generate sub-band noise signals. Values ofthe generated sub-band noise signals may be (or substantially) equal,i.e., V_(Y1)≈V_(Y2).

The first microphone 5212-i may process the received voice signal andgenerate a total voice signal which may be represented by Equation (11)below:V ₁ =V _(J1) +V _(Y1),  (11)

The second microphone 5214-i may process the received voice signal andgenerate a total voice signal which may be represented by Equation (12)below:V ₂ =V _(J2) +V _(Y2),  (12)

To eliminate the noise in the received voice signal, a differenceoperation may be performed between the total voice signal generated bythe first microphone 5212-i, and the total voice signal generated by thesecond microphone 5214-i. The difference operation may be represented byEquation (13) below:V=V ₁ −V ₂=(V _(J1) −V _(J2))+(V _(Y1) −V _(Y2))≈V _(J1) −V _(J2),  (13)

Further, actual sub-band voice signals (i.e., V_(J1) or V_(J2)) send bythe main sound source and actually received by the first microphone5212-i and/or the second microphone 5214-i may be determined accordingto a result of the difference operation of the sub-band voice signalsdetermined based on Equation (13), the distance between the firstmicrophone 5212-i and the main sound source, and the distance betweenthe second microphone 5214-i and the main sound source. In someembodiments, the difference results of sub-band voice signals may beinput into a synthesis device (not shown) for further processing afterthe difference results being enhanced and amplified, and a target signalmay be generated. The target signal may be broadcast to the user via anacoustic driver 5240 and/or an acoustic driver 5250.

In some embodiments, the first microphone set 5212 and/or the secondmicrophone set 5214 may be disposed on the temple 5200A and/or a frame5270 (as shown in FIG. 52A and FIG. 52B). To improve the quality of thegenerated sub-band voice signals, the difference result of the sub-bandvoice signals determined according to Equation (13) may be relativelygreat, i.e., V_(J1)>>V_(J2). In some embodiments, an installationposition of the first microphone set 5212 may relatively close to themain sound source, and an installation position of the second microphoneset 5214 may be relatively far away from the main sound source. In someembodiments, a baffle or the like may be disposed between two microphonearrays. For example, the first microphone set 5212 may be disposed at afront end 5222 of the temple 5200A, and the second microphone set 5214may be disposed at a rear end of the temple 5224. When the user wearsthe glasses with the temple 5200A, the auricle may increase the distancebetween the first microphone set 5212 and the second microphone set5214, and the auricle may be regarded as the baffle between the firstmicrophone set 5212 and the second microphone set 5214. In someembodiments, the distance between the first microphone set 5212 and themain sound source may be the same as the distance between the microphonearray 5010 as shown in FIG. 50A or the microphone array 5110 as shown inFIG. 51A and the main sound source. In some embodiments, a distance d(shown in FIG. 52A or 52B) between the first microphone set 5212 and thesecond microphone set 5214 may be not less than 0.2 centimeters, 0.4centimeters, 0.6 centimeters, 0.8 centimeters, 1 centimeters, 2centimeters, 3 centimeters, 4 centimeters, 5 centimeters, 6 centimeters,7 centimeters, 8 centimeters, 9 centimeters, 10 centimeters, 11centimeters, 12 centimeters, 13 centimeters, 14 centimeters, 15centimeters, 17 centimeters, 19 centimeters, 20 centimeters, etc.

In some embodiments, a distance between microphones of each pair ofmicrophones in a microphone array may be different. A distance betweenlow-frequency microphones may be greater than a distance betweenhigh-frequency microphones. FIG. 53 is a schematic diagram illustratingexemplary glasses 5300 according to some embodiments of the presentdisclosure. As shown in FIG. 53, a microphone array in the glasses 5300may include at least one pair of low-frequency microphones (e.g., alow-frequency microphone 5310 and a low-frequency microphone 5320) andat least one pair of high-frequency microphones (e.g., a high-frequencymicrophone 5330 and a high-frequency microphone 5340). A distancebetween the low frequency microphone 5310 and the low-frequencymicrophone 5320 may be greater than a distance between the highfrequency microphone 5330 and the high frequency microphone 5340.Different distances of microphones may be determined for differentfrequencies, thereby improving the sound reception performance of theglasses 5300. Specifically, when a position of a far-field sound sourceis constant, a frequency of a low-frequency sound may be relatively lowand a period of the low-frequency sound may be relatively long.Increasing the distance between the low-frequency microphone 5310 andthe low-frequency microphone 5320 may improve the sound reception effectof the near-field sound and may not increase the low-frequency noise inthe far-field (as a phase shift caused by the distance between thelow-frequency microphone 5310 and the low-frequency microphone 5320 mayonly account for a relatively small part of the period). Forhigh-frequency sounds, the frequency may be relatively great and theperiod may be relatively short. As the distance between thehigh-frequency microphone 5330 and the high-frequency microphone 5340decreases, a phase difference of far-field high-frequency noisescollected by the high-frequency microphone 5330 and the high-frequencymicrophone 5340 may gradually decrease, thereby eliminating long-rangehigh-frequency noises. The distance between the high-frequencymicrophones may be set smaller than the distance between thelow-frequency microphones, and different operations may be performed toreduce the noise, the far-field noise (e.g., a far-field noise mayinclude a far-field low-frequency noise and a far-field high-frequencynoise) may be eliminated or approximately eliminated. It should be notedthat positions of the low-frequency microphone 5310, the low-frequencymicrophone 5320, the high-frequency microphone 5330, and thehigh-frequency microphone 5340 in FIG. 53 may be only exemplary, andeach of the microphones may be disposed at a suitable position of theglasses 5300. For example, the low-frequency microphone 5310 and thelow-frequency microphone 5320 may be disposed in the frame, thehigh-frequency microphone 5330 and the high-frequency microphone 5340may be disposed in a temple. As another example, the low-frequencymicrophone 5310 may be disposed in the frame, the low-frequencymicrophone 5320, the high-frequency microphone 5330, and thehigh-frequency microphone 5340 may be disposed in the temple. In someembodiments, a range of the distance d_(l) between the low-frequencymicrophone 5310 and the low-frequency microphone 5320 may be 0.8centimeters-20 centimeters, 1 centimeters-18 centimeters, 1.2centimeters-16 centimeters, 1.4 centimeters-14 centimeters, 1.6centimeters-12 centimeters, 1.8 centimeters-10 centimeters, 2centimeters-8 centimeters, 2.2 centimeters-6 centimeters, 2.4centimeters-4 centimeters, 2.6 centimeters-3.8 centimeters, 2.2centimeters-6 centimeters, 2.4 centimeters-4 centimeters, 2.6centimeters-3.8 centimeters, 2.8 centimeters-3.6 centimeters, 3centimeters, etc. . . . . In some embodiments, a range of the distanced_(h) between the high-frequency microphone 5330 and the high-frequencymicrophone 5340 may be 1 millimeters-12 millimeters, 1.2 millimeters-11millimeters, 1.2 millimeters-10 millimeters, 1.4 millimeters-9millimeters, 1.6 millimeters-8 millimeters, 1.8 millimeters-7.5millimeters, 2 millimeters-7 millimeters, 2.5 millimeters-6.5millimeters, 3 millimeters-6 millimeters, 3.5 millimeters-5.5millimeters, 4 millimeters-5.3 millimeters, 5 millimeters, etc. In someembodiments, for a human voice, a frequency band of the human voice maybe mainly concentrated in a middle and low-frequency band. Thelow-frequency microphone 5310 may be disposed to be closer to the mainsound source than the high-frequency microphone 5330, thereby improvingthe intensity of a picked-up middle and low-frequency band signal. Thedistance between the low-frequency microphone 5310 and the main soundsource may be the same as the distance between the microphone array 5010and the main sound source, which is not repeated herein.

It should be noted that the descriptions regarding the glasses (e.g.,the glasses 4900, the glasses 5200B, the glasses 5300, etc.) and/or thetemple (e.g., the temples 4920, the temple 5200A, etc.) may be intendedto be illustrative, which do not limit the scope of the presentdisclosure. It should be understood that, after understanding theprinciple of the system, those skilled in the art may make variouschanges and modifications in forms and details to the application fieldsof the method and system without departing from the principle. However,the changes and modifications may not depart from the scope of thepresent disclosure. For example, the lenses 4930 may be omitted from theglasses 4900. As another example, the glasses 4900 may include one lens.The stabilization unit 5260 may be integrally formed with the temple5200A or may be detachably disposed on the temple 5200A.

In some embodiments, a microphone noise reduction system of the glasses(e.g., the glasses 4900, the glasses 5200B, the glasses 5300, etc.) maypick up the voice signal of the user wearing the glasses through a soundhole, process the voice signal and generate a target signal, andtransmit the target signal to an object or a device that the glasses maybe communicated with. An acoustic output device in the glasses mayreceive an audio signal transmitted by the object or the devicecommunicated with the glasses, convert the audio signal into a voicesignal, and output the audio signal to the user wearing the glassesthrough the sound hole. In some embodiments, the glasses may generate acontrol instruction according to a received voice signal, and controlone or more functions of the glasses. For example, the glasses maygenerate a control instruction according to a received voice to adjustthe transmittance of at least one of the lenses, so as to pass the lightwith different luminous fluxes. In some embodiments, the glasses mayautomatically adjust the light transmittance and/or haze degreeaccording to the received instruction, and call or turn off amini-projection device (not shown) to realize free switching among anormal mode, a VR mode, an AR mode, etc. For example, after the glassesreceive an instruction to switch to the AR mode, the transmittance ofthe lenses may be controlled to be decreased, and the AR image or videomay be projected in front of the user's sight by calling the miniprojection device. As another example, when the glasses receive aninstruction to switch to the VR mode, the haze degree of the lenses maybe controlled to be risen to close to 100%, and a VR image or video maybe projected on the inside of the lenses by calling the mini projectiondevice.

An acoustic output device (e.g., the glasses 4900, the glasses 5200B,the glasses 5300) described in some embodiments of the presentdisclosure may use microphones with different frequency responses,thereby improving the sensitivity of the microphone array for voicesignals with various frequency bands, and improving the stability of thefrequency response curve of the glasses for voice signals with fullfrequency band, and improving the sound reception performance of theacoustic output device. When using the glasses, the sub-band noisereduction technique may be adopted, thereby reducing the noises in thevoice signals. In addition, the glasses may use a sub-band sound leakagereduction technique, thereby reducing the sound leakage of the glassesand improving the user's experience.

FIG. 54 is a schematic diagram illustrating exemplary glasses 5400according to some embodiments of the present disclosure. As shown inFIG. 54, the glasses 5400 may include a frame and one or more lenses5440. The frame may include a temple 5410, a temple 5420, a lens frame5430, and a bridge 5450. The temple 5410 and the temple 5420 may beconfigured to support the lens frame 5430 and the lens 5440, andimmobilize the glasses 5400 on the user's face. The lens frame 5430 maybe configured to support the lenses 5440. The bridge 5450 may beconfigured to immobilize the glasses 5400 on the nose of the user.

A plurality of components configured to implement different functionsmay be disposed in the glasses 5400. The plurality of components mayinclude a power source, an acoustic driver, a microphone, a Bluetoothunit, and a controller. The power source may be configured to supplypower. The acoustic driver may be configured to generate sound. Themicrophone may be configured to detect external sound. The Bluetoothunit may be configured to connect other devices. The controller may beconfigured to control operations of other components. In someembodiments, the temple 5410 and/or the temple 5420 may include a hollowstructure configured to accommodate the plurality of components.

A plurality of hole-shaped structures may be disposed on the glasses5400. For example, as shown in FIG. 54, a guiding hole 5411 may bedisposed on a side of the temple 5410 and/or the temple 5420, which awayfrom the user's face. The guiding hole 5411 may be connected to one ormore acoustic drivers disposed inside the glasses 5400 and configured tooutput the sound generated by the acoustic drivers. In some embodiments,the guiding hole 5411 may be disposed at a position of the temple 5410and/or temple 5420 which may be close to the user's ear, for example, aposition on a rear end of the temple 5410 and/or the temple 5420, whichis away from the lens frame 5430, a position of a bending portion of thetemple 5410 and/or the temple 5420. In some embodiments, the glasses5400 may include a power source interface 5412 configured to charge thepower source of the glasses 5400. The power source interface 5412 may bedisposed on the temple 5410 and/or a side of the temple 5420 facing theuser's face. The exemplary power source interface may include a dockcharging interface, a direct current (DC) charging interface, auniversal serial bus (USB) charging interface, a lightning charginginterface, a wireless charging interface, or the like, or anycombination thereof. In some embodiments, the glasses 5400 may includeone or more sound inlets 5413 configured to transmit external sound(e.g., the user's voice, environmental sound, etc.) to the microphone ofthe glasses 5400. The sound inlet 5413 may be disposed on a position ofthe glasses 5400, where the user's voice may be easily acquired, forexample, a position of the temple 5410 and/or 5420 close to the user'smouth, a lower side of the lens frame 5430 close to the user's mouth,the bridge 5450, or the like, or any combination thereof. In someembodiments, a shape, a size, a count, etc., of the plurality ofhole-like structures on the glasses 5400 may be determined based onactual needs. For example, the shape of each of the plurality ofhole-like structures may include a square, a rectangle, a triangle, apolygon, a circle, an ellipse, an irregular shape, etc.

In some embodiments, one or more buttons may be also disposed on theglasses 5400 to realize the interaction between the user and the glasses5400. As shown in FIG. 54, the one or more buttons may include a powersource button 5421, a sound adjustment button 5422, a playback controlbutton 5423, a Bluetooth button 5424, or the like, or any combinationthereof. The power source button 5421 may include a power-on button, apower-off button, a power sleep button, or the like, or any combinationthereof. The sound adjustment button 5422 may include a volume increasebutton, a volume decrease button, or the like, or any combinationthereof. The play control button 5423 may include a play button, a pauseplay button, a resume play button, a playing call button, a hang-up callbutton, a hold call button, or the like, or any combination thereof. TheBluetooth button 5424 may include a Bluetooth connection button, aBluetooth off button, a connection object selection button, or the like,or any combination thereof. In some embodiments, the plurality ofbuttons may be disposed on the plurality of components of the glasses5400. For example, the power source button may be disposed on the temple5410, the temple 5420, or the lens frame 5430. In some embodiments, theone or more buttons may be disposed in one or more control devices. Theglasses 5400 may be connected to the one or more control devices in awired or wireless manner. The one or more control devices may transmitinstructions input by the user to the glasses 5400, thereby controllingthe operation of plurality of components of the glasses 5400.

In some embodiments, the glasses 5400 may include one or more indicatorsto indicate information related to one or more components of the glasses5400. For example, the indicator may be configured to indicate a powersource state, a Bluetooth connection state, a playing state, or thelike, or any combination thereof. In some embodiments, the indicator mayuse different states (e.g., different colors, different times, etc.) toindicate related information of the one or more components of theglasses 5400. As an example, when a power source indicator light is red,it may indicate that the power source is in a state of power shortage;when the power source indicator is green, it may indicate that the powersource is in a state of power saturation. As another example, aBluetooth indicator light may flash intermittently, which may indicatethat Bluetooth is connecting; the Bluetooth indicator light may be blue,which may indicate that the Bluetooth connection is successful.

In some embodiments, the temple 5410 and/or the temple 5420 may includea protective cover. The protective cover may be made of soft materialwith certain elasticity, such as silica gel, rubber, etc., to provide abetter touch for the user.

In some embodiments, the frame may be integrally formed, or may beassembled via an inserting connection, a snapping connection, or thelike, or any combination thereof. In some embodiments, the material ofthe frame may include steel, alloy, plastic, and single or compositematerials. The steel material may include stainless steel, carbon steel,etc. The alloy may include aluminum alloy, chromium-molybdenum steel,scandium alloy, magnesium alloy, titanium alloy, magnesium-lithiumalloy, nickel alloy, or the like, or any combination thereof. Theplastic may include Acrylonitrile Butadiene Styrene (ABS), Polystyrene(PS), High Impact Polystyrene (HIPS), Polypropylene (PP), PolyethyleneTerephthalate (PET), Polyester (PES), Polycarbonate (PC), Polyamides(PA), Polyvinyl Chloride (PVC), Polyethylene and Blown Nylon, etc. Thesingle or composite material may include glass fiber, carbon fiber,boron fiber, graphite fiber, graphene fiber, silicon carbide fiber oraramid fiber or other reinforcing materials, a composite of otherorganic and/or inorganic materials, such as glass fiber reinforcedunsaturated polyester, epoxy resin or phenolic resin matrix composed ofvarious types of glass fiber reinforced plastic, etc.

It should be noted that the descriptions of the glasses 5400 in FIG. 54are intended to be illustrative, which does not limit the scope of thepresent disclosure. Various substitutions, modifications, and changesmay be obvious to those skilled in the art. For example, the glasses5400 may include one or more cameras configured to collect environmentalinformation (e.g., capturing the scene in front of the user). As anotherexample, the glasses 5400 may include one or more projectors forprojecting an image (e.g., an image seen by the user through the glasses5400) onto a display screen.

FIG. 55 is a schematic diagram illustrating one or more components of anexemplary acoustic output device 5500 according to some embodiments ofthe present disclosure. As shown in FIG. 55, the acoustic output device5500 may include an earphone core 5510, a Bluetooth module 5520, abutton module 5530, a power source module 5540, a controller 5550, anauxiliary function module 5560, and a flexible circuit board module5570.

The earphone core 5510 may be configured to convert a signal containingaudio information into a voice signal. The audio information may includea video, an audio file with a specific data format, or data or a filethat may be converted into sound. The signal containing audioinformation may include an electrical signal, an optical signal, amagnetic signal, a mechanical signal, or the like, or any combinationthereof. During the conversion process of the signal, a plurality oftypes of energy may coexist and be converted. For example, an electricalsignal may be directly converted into mechanical vibration through theearphone core 5510 to generate sound. As another example, the audioinformation may be contained in an optical signal, and the earphone core5510 may perform the process of converting the optical signal into avibration signal. Other types of energy that may exist and be convertedduring a working process of the earphone core 5510 may include thermalenergy, magnetic field energy, or the like, or any combination thereof.

In some embodiments, the earphone core 5510 may include one or moreacoustic drivers. The acoustic drivers may be configured to convert anelectrical signal into a sound to be played. For example, the earphonecore 5510 may include at least two sets of acoustic drivers, and the atleast two sets of acoustic drivers may include at least one set ofhigh-frequency acoustic drivers and at least one set of low-frequencyacoustic drivers. Each of the at least two sets of the acoustic driversmay be configured to generate a sound with a specific frequency range,and propagate sound outward through at least two guiding holesacoustically coupled to the set of acoustic drivers. As another example,the earphone core 5510 may include at least one set of acoustic drivers,and the sound generated by the at least one set of acoustic drivers maybe propagated outward through at least two guiding holes acousticallycoupled to the at least one set of acoustic drivers. Optionally, the atleast two guiding holes may be respectively distributed on two sides ofa baffle (e.g., the auricle of a user), and the at least two guidingholes may have different acoustic routes to the user's ear canal. Moredescriptions regarding the acoustic drivers may be found elsewhere inthe present disclosure. See, e.g., FIG. 4 to FIG. 6B and the relevantdescriptions thereof.

The Bluetooth module 5520 may be configured to connect the acousticoutput device 5500 to other terminal devices. For example, the acousticoutput device 200 may be connected with a mobile phone through theBluetooth module 5520. Information (e.g., a song, a recording, etc.) ofthe mobile phone may be transmitted to the Bluetooth module 5520 basedon a Bluetooth protocol. The Bluetooth module 5520 may receive andprocess the information of the mobile phone, and send the processedinformation to other components of the acoustic output device 5500 forfurther processing. In some embodiments, the terminal device connectedwith the acoustic output device 5500 may include a smart home device, awearable device, a mobile device, a virtual reality device, an augmentedreality device, or the like, or any combination thereof. In someembodiments, the smart home device may include a smart lighting device,a control device of a smart electrical device, a smart monitoringdevice, a smart TV, a smart camera, a walkie-talkie, or the like, or anycombination thereof. In some embodiments, the wearable device mayinclude a bracelet, a helmet, a watch, clothing, a backpack, or thelike, or any combination thereof. In some embodiments, the mobile devicemay include a smartphone, a personal digital assistant (PDA), a gamingdevice, a navigation device, a point of sale (POS) device, an audio hoston a vehicle, or the like, or any combination thereof. In someembodiments, the virtual reality device and/or the augmented realitydevice may include a virtual reality helmet, virtual reality glasses, anaugmented reality helmet, augmented reality glasses, or the like, or anycombination thereof.

The Bluetooth module 5520 may perform communication in the 2.4 GHzIndustrial Scientific Medical (ISM) frequency band during thecommunication based on a wireless protocol. The ISM frequency band maybe used freely without a separate license. In some embodiments, in afrequency range below and above the ISM band, a guard band of 2 MHz anda guard band of 3.5 MHz may be set respectively to prevent interferencewith other devices. In some embodiments, when the Bluetooth module 5520communicates with other devices, a frequency hopping scheme may be used,for example, the frequency may be hopped 1600 times per second.

To connect with a device, the Bluetooth module 5520 may receive uniqueinformation of the device, which may include the received signalintensity indicator (RSSI) from the device. The unique information mayinclude a blocking unique identifier (OUI) of a cut-off access control(MAC) address, a Bluetooth address (BD ADDR), a type of the device, aname of the device, or the like, or any combination thereof. When theconnection is established, the information and/or signal may betransmitted according to a Bluetooth transmission protocol. ExemplaryBluetooth transmission protocols may include the Logical Link Controland Adaptation Protocol (L2CAP), the Radio Frequency Communication(RFCOMM), the Service Search Protocol (SDP), etc.

The button module 5530 may be configured to control the acoustic outputdevice 5500, and realize interaction between the user and the acousticoutput device 5500. The user may send an instruction to the acousticoutput device 5500 through the button module 5530 to control theoperation of the acoustic output device 5500. In some embodiments, thebutton module 5530 may include a power source button, a playback controlbutton, a sound adjustment button, a phone control button, a recordingbutton, a noise reduction button, a Bluetooth button, a return button,or the like, or any combination thereof. The power source button may beconfigured to control the power source 240 to turn on, off, sleep, orthe like, or any combination thereof. The playback control button may beconfigured to control the playback of a sound in the earphone core 5510,for example, playback information, pause playback information, continueplayback information, play the previous item, play the next item, playmode selection (e.g., a sports mode, a work mode, an entertainment mode,a stereo mode, a folk mode, a rock mode, a heavy bass mode, etc.),playback environment selection (e.g., indoor, outdoor, etc.), or thelike, or any combination thereof. The sound adjustment button may beconfigured to control the sound played by the earphone core 5510, forexample, increase a volume of the sound, decrease the volume of thesound, or the like. The phone control button may be configured tocontrol the answering, rejecting, hanging up, dialing back, holding,storing, etc., of a call. The record button may be configured to recordand store sound information. The noise reduction button may beconfigured to select the degree of noise reduction. For example, theuser may manually select a level or degree of noise reduction, or theacoustic output device 5500 may automatically select the level or degreeof noise reduction according to the detected environmental sound or theplayback mode selected by the user. The Bluetooth button may beconfigured to turn on Bluetooth, turn off Bluetooth, perform a Bluetoothmatching, perform a Bluetooth connection, select a connection device, orthe like, or any combination thereof. The return button may beconfigured to return to a previous menu, an interface, etc.

In some embodiments, the button module 5530 may include a physicalbutton, a virtual button, or the like, or any combination thereof. Forexample, when the button module 5530 is a physical button, the buttonmay be disposed outside a housing of the acoustic output device (e.g.,the glasses 5400). When the user wears the acoustic output device, thebutton may be not in contact with human skin and may be exposed on theoutside to facilitate the user's operation of the button. In someembodiments, an end surface of each button of the button module 5530 mayinclude an identification corresponding to its function. In someembodiments, the identification may include a text (e.g., Chinese andEnglish), symbols (e.g., a volume up button may be marked by “+,” and avolume down button may be marked by “−”). In some embodiments, a logomay be disposed on the button by means of laser printing, screenprinting, pad printing, laser filling, thermal sublimation, hollow text,or the like. In some embodiments, the logo on the button may be disposedon the peripheral surface of the housing around the boundary of thebutton, which may serve as the identification. In some embodiments, acontrol program installed in the acoustic output device may generate thevirtual button on the touch screen with an interactive function. Theuser may select the function, volume, file, etc., of the acoustic outputdevice through the virtual button. In addition, the acoustic outputdevice may both include a touch screen and a physical button.

In some embodiments, the button module 5530 may implement differentinteractive functions based on different operations of the user. Forexample, that the user clicks the button (a physical button or a virtualbutton) one time may realize, for example, pause/start of music,recording, etc. As another example, that the user clicks the buttontwice quickly may realize answering a call. As yet another example, thatthe user clicks the button regularly (e.g., tapping once every second,tapping twice in total) to perform a recording function. In someembodiments, the user's operation may include clicking, sliding,scrolling, or the like, or any combination thereof. For example, whenthe user's finger slides up and down on the surface of a button, thevolume up/down function may be realized.

In some embodiments, the function corresponding to the button module5530 may be customized by the user. For example, the user may adjust thefunction that the button module 5530 may implement through the settingof an application software. In addition, the user may set an operationmode (e.g., a count of clicking, a sliding gesture) to achieve aspecific function through the application software. For example, settingthe operation instruction corresponding to the answering call functionfrom one click to two clicks, or setting the operation instructioncorresponding to the switch to the next/previous song function from twoclicks to three clicks. The operation mode may be determined based onthe user's operation habit in a user-defined manner, thereby reducingoperating errors to a certain extent and improving user experience.

In some embodiments, the acoustic output device may be connected to anexternal device through the button module 5530. For example, theacoustic output device may be connected to a mobile phone through abutton (e.g., a button for controlling the Bluetooth module 5520) forcontrolling a wireless connection. Optionally, after the connection isestablished, the user may directly operate the acoustic output devicethrough the external device (e.g., a mobile phone) to implement one ormore functions.

The power source module 5540 may be configured to provide electricalenergy for other components of the acoustic output device 5500. In someembodiments, the power source module 5540 may include a flexible circuitboard, a battery, or the like. The flexible circuit board may beconfigured to connect the battery and the other components (e.g., theearphone core 5510) of the acoustic output device to provide electricalenergy for operations of the other components. In some embodiments, thepower source module 5540 may transmit state information thereof to thecontroller 5550 and receive an instruction from the controller 5550 toperform corresponding an operation. The state information of the powersource module 5540 may include an on/off state, a remaining power, ausage time of the remaining power, a charging time, or the like, or anycombination thereof.

The controller 5550 may generate the instruction to control the powersource module 5540 according to information of the one or morecomponents of the acoustic output device 5500. For example, thecontroller 5550 may generate a control instruction to control the powersource module 5540 to provide the earphone core 5510 with power togenerate a sound. As another example, when the acoustic output device5500 does not receive input information within a specific period, thecontroller 5550 may generate a control instruction to control the powersource module 5540 to enter the sleep state (i.e., stand by or readymode). In some embodiments, the battery of the power source module 5540may include an accumulator, a dry battery, a lithium battery, a Daniellbattery, a fuel cell, or the like, or any combination thereof.

Merely by way of example, the controller 5550 may receive a user's voicesignal from the auxiliary function module 5560, for example, “play asong.” By processing the voice signal, the controller 5550 may generatea control instruction related to the voice signal, for example,controlling the earphone core 5510 to obtain information of the song tobe played from a storage device (or other devices), and accordingly,generating an electrical signal to control the vibration of the earphonecore 5510, etc.

In some embodiments, the controller 5550 may include one or moreelectronic frequency division modules. The one or more electronicfrequency division modules may perform frequency division processing ona sound source signal. The sound source signal may be obtained from oneor more sound source devices (e.g., a memory for storing audio data)integrated into the acoustic output device. The sound source signal mayinclude an audio signal (e.g., an audio signal received from theauxiliary function module 5560) received by the acoustic output devicein a wired or wireless manner. In some embodiments, the electronicfrequency division modules may decompose the input sound source signalinto two or more frequency-divided signals containing differentfrequency components. For example, the electronic frequency divisionmodules may decompose the sound source signal into a firstfrequency-divided signal with high-frequency components and a secondfrequency-divided signal with low-frequency components. The signalsprocessed by the electronic frequency division modules may betransmitted to the acoustic driver of the earphone core 5510 in a wiredor wireless manner. More descriptions regarding the electronic frequencydivision module may be found elsewhere in the present disclosure. See,e.g., FIG. 4 and the relevant descriptions thereof.

In some embodiments, the controller 5550 may include a centralprocessing unit (CPU), an application-specific integrated circuit(ASIC), an application-specific instruction set processor (ASIP), agraphics processing unit (GPU), a physical processing unit (PPU), adigital signal processor (DSP), a field programmable gate array (FPGA),a programmable logic device (PLD), a controller, a microcontroller unit,a reduced Instruction set computer (RISC), a microprocessor, or thelike, or any combination thereof.

The auxiliary function module 5560 may be configured to receive anauxiliary signal and perform an auxiliary function. The auxiliaryfunction module 5560 may include one or more microphones, indicators,sensors, displays, or the like, or any combination thereof.Specifically, the auxiliary signals may include a state (e.g., an openstate, a closed state, a sleep state, a connection state, etc.) signalof the auxiliary function module 5560, a signal generated according tothe user operation (e.g., an input and output signal generated accordingto user's input through a button, a user's voice input), or the like, orany combination thereof. In some embodiments, the auxiliary functionmodule 5560 may transmit the received auxiliary signal to othercomponents of the acoustic output device 5500 in a wired or wirelessmanner for processing.

The sensor may be configured to detect information related to theacoustic output device 5500. For example, the sensor may be configuredto detect the user's fingerprint and transmit the detected fingerprintto the controller 5550. The controller 5550 may match the receivedfingerprint with a reference fingerprint stored in the acoustic outputdevice 5500 in advance. If the matching is successful, the controller5550 may generate an instruction to turn on the acoustic output device5500, and the instruction may be transmitted to each component of theacoustic output device 5500 to perform the operation of turning on theacoustic output device 5500. As another example, the sensor may beconfigured to detect the position of the acoustic output device 5500.When the sensor detects that the acoustic output device 5500 is detachedfrom the user's face, the sensor may transmit the detected informationto the controller 5550, and the controller 5550 may generate aninstruction to pause or close the playback of the acoustic output device5500. In some embodiments, the sensor may include a ranging sensor(e.g., an infrared ranging sensor, a laser ranging sensor, etc.), aspeed sensor, a gyroscope, an accelerometer, a positioning sensor, adisplacement sensor, a pressure sensor, a gas sensor, a light sensor, atemperature sensor, a humidity sensor, a fingerprint sensor, an imagesensor, an iris sensor (e.g., a camera, etc.), or the like, or anycombination thereof.

The flexible circuit board module 5570 may be configured to connectdifferent components of the acoustic output device 5500. The flexiblecircuit board module 5570 may include a flexible circuit board (FPC). Insome embodiments, the flexible circuit board module 5570 may include oneor more bonding pads and/or one or more flexible wires. The one or morebonding pads may be configured to connect one or more components of theacoustic output device 200 or other bonding pads. One or more flexiblewires may be configured to connect components and the bonding pads, abonding pad and another bonding pad of the acoustic output device 200,or the like. In some embodiments, the flexible circuit board module 5570may include one or more flexible circuit boards. Merely by way ofexample, the flexible circuit board module 5570 may include a firstflexible circuit board and a second flexible circuit board. The firstflexible circuit board may be configured to connect two or more of themicrophones, the earphone core 5510, and the controller 5550. The secondflexible circuit board may be configured to connect two or more of thepower source module 5540, the earphone core 5510, the controller 5550,etc. In some embodiments, the flexible circuit board module 5570 mayinclude an integral structure that includes one or more regions. Forexample, the flexible circuit board module 5570 may include a firstregion and a second region. The first region may include flexible wiresfor connecting the bonding pads on the flexible circuit board module5570 and other components of the acoustic output device 200. The secondregion may include one or more bonding pads. In some embodiments, thepower source module 5540 and/or the auxiliary function module 5560 maybe disposed on the flexible circuit board module 5570, and connected tothe flexible circuit board module 5570 through the flexible wires on theflexible circuit board module 5570 (e.g., the bonding pads of theflexible circuit board module 5570). More descriptions regarding theflexible circuit board units may be found elsewhere in the presentdisclosure. See, e.g., FIG. 56 and FIG. 57, and the descriptionsthereof.

In some embodiments, one or more of the earphone core 5510, theBluetooth module 5520, the button module 5530, the power source module5540, the controller 5550, the auxiliary function module 5560, and theflexible circuit board module 5570 may be disposed in the frame of theglasses 5400. Specifically, one or more electronic components may bedisposed in the hollow structure of the temple 5410 and/or the temple5420. The electronic components disposed in the temple 5410 and/or thetemple 5420 may be connected and/or communicated in a wired or wirelessmanner. The wired manner may include a metal cable, an optical cable, ahybrid cable, or the like, or any combination thereof. The wirelessmanner may include a local area network (LAN), a wide area network(WAN), Bluetooth, ZigBee, near field communication (NFC), or the like,or any combination thereof.

It should be noted that the descriptions of the acoustic output device5500 in FIG. 55 are intended to be illustrative, which does not limitthe scope of the present disclosure. Various substitutions,modifications, and changes may be obvious to those skilled in the art.For example, the acoustic output device 5500 may include a soundrecognition function, an image recognition function, a motionrecognition function, or the like, or any combination thereof. In thiscase, the acoustic output device 5500 may perform a correspondingfunction by recognizing the user's voice, motion, or the like. In someembodiments, the recognized action may include the count (or the number)and/or frequency of the user's eye blinks, the number, direction and/orfrequency of the user's head nodding and/or shaking, and the number,direction, frequency, and form of the user's hand movements. Forexample, the user may interact with the acoustic output device 5500through the number and/or frequency of eye blinks. Specifically, theuser may blink twice in series to turn on the sound playing function ofthe acoustic output device 5500, the user may blink three times to turnoff the Bluetooth function of the acoustic output device 5500, etc. Asanother example, the user may realize the interaction with the acousticoutput device 5500 through the number, direction, and/or frequency ofnodding. Specifically, the user may answer the call by nodding once, orthe user may refuse a call or turn off the music playback by shaking thehead once. As yet another example, the user may interact with theacoustic output device 5500 through a gesture, etc. Specifically, theuser may open the acoustic output device 5500 by extending his palm,close the acoustic output device by holding his fist, or take a photo byextending a “scissors” gesture. These changes and modifications arestill within the protection scope of the present disclosure.

FIG. 56 is a schematic diagram illustrating a connection of componentsof an acoustic output device according to some embodiments of thepresent disclosure. For illustration purposes, merely a connection ofsome exemplary components is shown in FIG. 56. As shown in FIG. 56, aflexible circuit board module 5570 may include one or more first bondingpads (i.e., first bonding pads 5572-1, 5572-2, 5572-3, 5572-4, 5572-5,5572-6), one or more second bonding pads (i.e., second bonding pads5574-1, 5574-2, 5574-3, 5574-4), and one or more wires. At least onefirst bonding pad in the flexible circuit board module 5570 may beconnected to at least one second bonding pad in a wired manner,respectively. For example, the first bonding pad 5572-1 and the secondbonding pad 5574-1 may be connected via a flexible wire, the firstbonding pad 5572-2 and the second bonding pad 5574-2 may be connectedvia a flexible wire, the first bonding pad 5572-5 and the second bondingpad 5574-3 may be connected via a flexible wire, the first bonding pad5572-5 and the second bonding pad 5574-3 may be connected via a flexiblewire, or the first bonding pad 5572-6 and the second bonding pad 5574-4may be connected via a flexible wire.

In some embodiments, each of at least a portion of the components of theacoustic output device 5500 may be connected with one or more bondingpads. For example, the earphone core 5510 may be electrically connectedwith the first bonding pad 5572-1 and the first bonding pad 5572-2through a wire 5512-1 and a wire 5512-2, respectively. The auxiliaryfunction module 5560 may be connected with the first bonding pad 5572-5and the first bonding pad 5572-6 through a wire 5562-1 and a wire5562-2, respectively. The controller 5550 may be connected with thesecond bonding pad 5574-1 through a wire 5552-1, with the second bondingpad 5574-2 through a wire 5552-2, with the first bonding pad 5574-3through a wire 5552-3, with the first bonding pad 5572-4 through a wire5552-4, with the second bonding pad 5574-3 through a wire 5552-5, and/orwith the second pad 5574-4 through a wire 5552-6. The power sourcemodule 5540 may be connected with the first bonding pad 5574-3 through awire 5542-1 and may be connected with the first bonding pad 5572-4through a wire 5542-2. The wire may include a flexible wire or anexternal wire. The external wire may include an audio signal wire, anauxiliary signal wire, or the like, or any combination thereof. Theaudio signal wire may include a wire that is connected to the earphonecore 5510 and transmit a voice signal to the earphone core 5510. Theauxiliary signal wire may include a wire that is connected with theauxiliary function module 5560 and perform signal transmission with theauxiliary function module 5560. For example, the wire 5512-1 and thewire 5512-2 may include voice signal wires. As another example, the wire5562-1 and the wire 5562-2 may include auxiliary signal wires. As yetanother example, the wire 5552-1 to the wire 5552-6 may include theaudio signal wires and/or the auxiliary signal wires. In someembodiments, the acoustic output device 5500 may include one or moreburied grooves for placing wire and/or flexible leads.

As an example, the user of an acoustic output device (e.g., the glasses5400) may send a signal (e.g., a signal to play music) to the acousticoutput device by pressing a button. The signal may be transmitted to thefirst bonding pad 5572-5 and/or the first bonding pad 5572-6 of theflexible circuit board module 5570 through the wire 5562-1 and/or thewire 5562-2, and then to the second bonding pad 5574-3 and/or the secondbonding pad 5574-4 through the flexible lead. The signal may betransmitted to the controller 5550 through the wire 5552-5 and/or thewire 5552-6 connected to the second bonding pad 5574-3 and/or the secondbonding pad 5574-4. The controller 5550 may analyze and process thereceived signal, and generate a corresponding instruction according tothe processed signal. The instruction generated by the controller 5550may be transmitted to the flexible circuit board module 5570 through oneor more wires of the wires 5552-1 to 5552-6. The instruction generatedby the controller 5550 may be transmitted to the earphone core 5510through the wire 5512-1 and/or the wire 5512-2 connected with theflexible circuit board module 5570, and control the earphone core 5510to play the music. The instruction generated by the controller 5550 maybe transmitted to the power source module 5540 through the wire 5542-1and/or the wire 5542-2 connected with the flexible circuit board module5570, and the power source module 5540 may be controlled to provideother components with the power required to play the music. Theconnection of the flexible circuit board module 5570 may simplify theleading manner between different components of the acoustic outputdevice 5500, reduce the mutual influence of the wires and/or flexibleleads, and save the space occupied by the wires and flexible leads ofthe acoustic output device 5500.

FIG. 57 is a schematic diagram illustrating an exemplary power source5700 according to some embodiments of the present disclosure. As shownin FIG. 57, the power source 5700 may include a battery 5710 and aflexible circuit board 5720. In some embodiments, the battery 5710 andthe flexible circuit board 5720 may be disposed in a housing of anacoustic output device (e.g., the temple 5410 or the temple 5420 of theglasses 5400).

The battery 5710 may include a body area 5712 and a sealing area 5714.In some embodiments, the sealing area 5714 may be disposed between theflexible circuit board 5720 and the body area 5712, and may be connectedwith the flexible circuit board 5720 and the body area 5712. Theconnection between the sealing area 5714 and the flexible circuit board5720 and the connection between the sealing area 5714 and the body area5712 may include a fixed connection and/or a movable connection. In someembodiments, the sealing area 5714 and the body area 5712 may be tiled,and a thickness of the sealing area 5714 may be equal to or less than athickness of the body area 5712, thus a stepped structure may be formedbetween at least one side surface of the sealing area 5714 and a surfaceof the body area 5712 adjacent to the at least one side surface of thesealing area 5714. In some embodiments, the battery 5710 may include apositive electrode and a negative electrode. The positive electrode andthe negative electrode may be directly connected or indirectly connectedwith other components of the acoustic output device (e.g., through theflexible circuit board 5720), respectively.

In some embodiments, the flexible circuit board 5720 may include a firstboard 5721 and a second board 5722. The first board 5721 may include oneor more first bonding pads, one or more second bonding pads, andflexible wires. The first bonding pads may include a third bonding padset 5723-1, a third bonding pad set 5723-2, a third bonding pad set5723-3, and a third bonding pad set 5723-4. Each third bonding pad setmay include one or more fourth bonding pads, for example, two fourthbonding pads. The second bonding pads may include a second bonding pad5725-1 and a second bonding pad 5725-2. One or more fourth bonding padsin each set of the third bonding pad sets in the first bonding pads mayconnect two or more components of the acoustic output device. Forexample, a fourth bonding pad in the third bonding pad set 5723-1 may beconnected to an earphone core (e.g., the earphone core 5510) through anexternal wire, and a fourth bonding pad may be connected to anotherfourth bonding pad in the third bonding pad set 5723-1 through aflexible wire disposed on the first board 5721, and the other fourthbonding pads in the third bonding pad set 5723-1 may be connected withthe controller (e.g., the controller 5550) through one or more externalwires, thereby realizing communication between the earphone core and thecontroller by connecting the earphone core and the controller. Asanother example, a fourth bonding pad in the third bonding pad set5723-2 may be connected with the Bluetooth module 5520 through anexternal wire, a fourth bonding pad in the third bonding pad set 5723-2may be connected with the other fourth bonding pads in the third bondingpad set 5723-2 through a flexible wire, and/or another fourth bondingpad in the third bonding pad set 5723-2 may be connected with theearphone core 5510 through an external wire, thereby connecting theearphone core 5510 with the Bluetooth module 5520, thus the acousticoutput device may play audio information through a Bluetooth connection.One or more second bonding pads (e.g., the second bonding pad 5725-1,the second bonding pad 2725-2) may be configured to connect one or morecomponents of the acoustic output device to the battery 5710. Forexample, the second bonding pad 5725-1 and/or the second bonding pad5725-2 may be connected with the earphone core through one or moreexternal wires, and/or the second bonding pad 5725-1 and/or the secondbonding pad 5725-2 may be connected with the battery 5710 through aflexible wire disposed on the second board 5722, thereby connecting theearphone core and the battery 5710.

The first bonding pads 5723 and the second bonding pads 5725 may bedisposed via various manners. For example, all the bonding pads may bedisposed at intervals along a straight line or arranged at intervals inother shapes. In some embodiments, one or more sets of first bondingpads 5723 may be disposed at intervals along a length direction of thefirst board 5721 as indicated by arrow A in FIG. 57. One or more fourthbonding pads in each third bonding pad set in one or more first bondingpads 5723 may be disposed along a width direction of the first board5721 as indicated by arrow B in FIG. 57, which may be staggered andarranged at intervals along the width direction of the first board 5721.The one or more second bonding pads 5725 may be disposed in a middlearea of the first board 5721. The one or more second bonding pads 5725may be disposed along the length direction of the first board 5721. Inthis case, the formation of a flush interval space between the twoadjacent sets of the first bonding pads 5723 may be avoided, therebyimproving the distribution uniformity of intensity of the first board5721, reducing bending between two adjacent sets of the first bondingpads 5723, and reducing the probability that the first board 5721 breaksoff due to the bending, and protecting the first board 5721. Inaddition, distances between the bonding pads may be reduced, therebyfacilitating soldering and reducing the short circuit between differentbonding pads.

In some embodiments, the second board 5722 may include one or moreflexible wires 422 configured to connect the bonding pads on the firstboard 5721 and the battery 5710. For example, the second board 5722 mayinclude two flexible wire s. One end of each of the two flexible wiresmay be connected with one of the positive and negative electrodes of thebattery 5710, and another end of each of the two flexible leads may beconnected with one of the bonding pads on the first board 5721. It isnot necessary to dispose additional bonding pads to lead the positiveand negative electrodes of the battery 5710, thereby reducing the count(or the number) of the bonding pads and simplifying the structure andprocess of the power source 5700. Due to only flexible wires may bedisposed on the first board 5721, in some embodiments, the second board5722 may be bent according to specific conditions. For example, one endof the first board 5721 may be fixed to the battery 5710 by bending thesecond board 5722, thereby reducing the bulk of the power source 5700,saving the space of the housing of the acoustic output device, andimproving space utilization. As another example, by folding the secondboard 5722, the first board 5721 may be attached to a side surface ofthe battery 5710, the second board 5722 and the battery 5710 may bestacked, thereby greatly reducing the space occupied by the power source5700.

In some embodiments, the flexible circuit board 5720 may be a whole, andthe first board 5721 and the second board 5722 may be two areas of theintegral flexible circuit board 5720. In some embodiments, the flexiblecircuit board 5720 may be divided into two independent parts. Forexample, the first board 5721 and the second board 5722 may be twoindependent boards. In some embodiments, the flexible printed board 5720may be disposed in the space formed by the body area 5712 and/or thesealing area 5714 of the battery 5710, and it is not necessary toprovide a separate space for the flexible circuit board 5720, therebyimprove the space utilization of the power source 5700.

In some embodiments, the battery source 5700 may further include a hardcircuit board 5716. The hard circuit board 5716 may be disposed in thesealing area 5714. The positive and negative electrodes of the battery5710 may be disposed on the hard circuit board 5716. Alternatively, aprotection circuit may be disposed on the hard circuit board 5716 toprotect the battery 5710 from overloading. The end of the second board5722 away from the first board 5721 may be fixedly connected with thehard circuit board 5716, and the flexible wires on the second board 5722may be connected with the positive and negative electrodes of thebattery 5710. In some embodiments, the second board 5722 and the hardcircuit board 5716 may be pressed together during the manufacture of thepower source 5700.

In some embodiments, shapes of the first board 5721 and the second board5722 may be determined according to actual conditions. The shape of eachof the first board 5721 and the second board 5722 may include a square,a rectangle, a triangle, a polygon, a circle, an ellipse, an irregularshape, or the like. In some embodiments, the shape of the second board5722 may match a shape of the sealing area 5714 of the battery 5710. Forexample, the shape of the sealing area 5714 and the second plate 5722may both be rectangular, and the shape of the first plate 5721 may alsobe rectangular. In addition, the first board 5721 may be placed at oneend of the second board 5722 along the length direction of the secondboard 5722, and the length direction of the first board 5721 (i.e., thedirection denoted by arrow A) may be perpendicular to the lengthdirection of the second board 5722 (i.e., the direction denoted by arrowB). Specifically, the second board 5722 may be connected to a middlearea in the length direction of the first board 5721, and the firstboard 5721 and the second board 5722 may form a T-shaped structure.

It should be noted that the descriptions of the battery 5710 and theflexible circuit board 5720 of the power source 5700 of the acousticoutput device may be intended to be illustrative, which does not limitthe scope of the present disclosure. Various substitutions,modifications, and changes may be obvious to those skilled in the art.For example, the acoustic output device may include auxiliary functionunits such as a voice control unit, a microphone unit, etc. Suchmodifications and changes are still within the protection scope of thepresent disclosure.

In some embodiments, an acoustic output device (e.g., the glasses 5400)may include a voice control system. The voice control system may beconfigured as a part of an auxiliary function unit (e.g., the auxiliaryfunction module 5560), or may be integrated into the acoustic outputdevice as an independent unit. As shown in FIG. 58, in some embodiments,a voice control system 5800 may include a receiving module 5802, aprocessing module 5804, a recognition module 5806, and a control module5808.

In some embodiments, the receiving module 5802 may be configured toreceive a voice control instruction and send the voice controlinstruction to the processing module 5804. In some embodiments, thereceiving module 5802 may include one or more microphones. In someembodiments, when the receiving module 5802 receives a voice controlinstruction issued by the user, for example, when the receiving module5802 receives a voice control instruction of “starting playing”, thevoice control instruction may be sent to the processing module 5804.

In some embodiments, the processing module 5804 may be communicated withthe receiving module 5802, generate an instruction signal according tothe voice control instruction, and send the instruction signal to therecognition module 5806.

In some embodiments, when the processing module 5804 receives the voicecontrol instruction issued by the user from the receiving module 5802through a communication connection, the processing module 5804 maygenerate the instruction signal according to the voice controlinstruction.

In some embodiments, the recognition module 5806 may be communicatedwith the processing module 5804 and the control module 5808, andconfigured to determine whether the instruction signal matches a presetsignal, and send a matching result to the control module 5808.

In some embodiments, when the recognition module 5806 determines that aninstruction signal matches the preset signal, the recognition module5806 may send the matching result to the control module 5808. Thecontrol module 5808 may control an operation of the acoustic outputdevice according to the instruction signal. For example, when thereceiving module 5802 receives a voice control instruction of “startplaying”, and the recognition module 5806 determines that theinstruction signal corresponding to the voice control instructionmatches the preset signal, the control module 5808 may automaticallyexecute the voice control instruction, that is, immediately startplaying audio data. When the instruction signal does not match thepreset signal, the control module 5808 may not execute the controlinstruction.

In some embodiments, the voice control system may include a storagemodule, and the storage module may be communicated with the receivingmodule 5802, the processing module 5804, and/or the recognition module5806. The receiving module 5802 may receive a preset voice controlinstruction and send the preset voice control instruction to theprocessing module 5804. The processing module 5804 may generate a presetsignal according to the preset voice control instruction, and send thepreset signal to the storage module. When the recognition module 5806 isneeded to match the instruction signal received by the receiving module5802 with the preset signal, the storage module may send the presetsignal to the recognition module 5806.

In some embodiments, the processing module 5804 may be furtherconfigured to remove an environment sound included in the voice controlinstruction.

In some embodiments, the processing module 5804 may perform a denoisingoperation on the voice control instruction. As used herein, a denoisingoperation refers to an operation performed to remove or reduce anenvironment sound included in the voice control instruction. Forexample, when in a complex environment, the receiving module 5802 mayreceive the voice control instruction and send the voice controlinstruction to the processing module 5804. Before the processing module5804 generates the instruction signal according to the voice controlinstruction, the voice control instruction may be denoised by theprocessing module 5804 to avoid the environment sound from affecting arecognition operation of the recognition module 5806. As anotherexample, when the receiving module 5802 receives the voice controlinstruction issued by the user who is on an outdoor road, the voicecontrol instruction may include a noisy environment sound such asvehicle driving sound, a whistling sound, etc. The processing module 302may perform the denoising operation on the voice control instruction toreduce the effect of the environment sound on the voice controlinstruction.

It should be noted that the descriptions of the voice control system maybe intended to be illustrative, which does not limit the scope of thepresent disclosure. For example, the receiving module and the processingmodule may be independent modules, or the receiving module and theprocessing module may be integrated into one single module. Suchmodifications and changes are still within the protection scope of thepresent disclosure.

In some embodiments, an acoustic output device (e.g., the glasses 5400)in some embodiments of the present disclosure may reduce the mutualeffect among wires and improve the sound quality of the acoustic outputdevice by simplifying a wiring manner of the wires. In some embodiments,the acoustic output device in some embodiments of the present disclosuremay be combined with a Bluetooth technique to reduce the mutual effectamong the wires, thereby improving the convenience of carrying,operating, and/or using the acoustic output device.

FIG. 59 is a cross-sectional view of an exemplary open binaural earphone5900 according to some embodiments of the present disclosure. FIG. 60 isa schematic diagram illustrating a sound generation structure 6000 of anexemplary open binaural earphone according to some embodiments of thepresent disclosure. In some embodiments, the sound generation structure6000 may be an exemplary embodiment of a sound generation structure 5905of the open binaural earphone 5900. FIG. 61 is a cross-sectional view ofa baffle 6100 of an exemplary open binaural earphone according to someembodiments of the present disclosure. In some embodiments, thecross-sectional view of the baffle 6100 in FIG. 61 may be an exemplaryembodiment of a cross-sectional view of a baffle of the open binauralearphone 5900 along a C-C section. As shown in FIG. 59, FIG. 60, andFIG. 61, the open binaural earphone 5900 may include a housing 5910, atleast one microphone 5920, one or more acoustic drivers 5930, and atleast one guiding tube (e.g., a guiding tube-1, a guiding tube-2, aguiding tube-3, a guiding tube-4, etc.) corresponding to the acousticdriver(s) 5930, a baffle 5950, a circuit board 5960, a Bluetooth module5970, and a power source module 5980. In some embodiments, the openbinaural earphone 5900 may further include an electronic frequencydivision unit (not shown in the figure, please refer to the electronicfrequency division unit 110). In some embodiments, the electronicfrequency division unit, the acoustic driver(s) 5930, and the guidingtube may be collectively referred to as an acoustic output device. Moredescriptions regarding the acoustic output device may be found elsewherein the present disclosure. See, e.g., FIG. 1 to FIG. 37 (e.g., theacoustic output device 100, the acoustic output device 300, the acousticoutput device 400, the acoustic output device 500, the acoustic outputdevice 600, the acoustic output device 1000, etc.) and the relevantdescriptions thereof.

In some embodiments, the electronic frequency division unit may bedisposed in the housing 5910. Exemplary electronic frequency divisionunits may include a passive filter, an active filter, an analog filter,a digital filter, or the like, or any combination thereof. In someembodiments, the acoustic driver(s) 5930 with different frequencyresponse characteristics (e.g., a low-frequency transducer, anintermediate-frequency transducer, and/or a high-frequency transducer)may be disposed, and the transducers with different frequency responsesmay output sound including different frequency components. In someembodiments, frequency division processing of an audio signal may alsobe implemented in acoustic routes. For example, the acoustic driver(s)5930 may generate a full-band sound, and the sound output by theacoustic driver(s) 5930 may be acoustically filtered in acoustic routeswith different acoustic impedances, and the sound output throughdifferent acoustic routes may have different frequency components. Moredescriptions regarding the frequency division based on acoustic routesmay be found elsewhere in the present disclosure. See, e.g., FIG. 4,FIGS. 7A to 8C and the relevant descriptions thereof. In someembodiments, the frequency division processing of the audio signal maybe implemented by two or more of the manners mentioned above.

Voice signals with different frequency components generated by theacoustic driver(s) 5930 may be output to the user from different guidingholes 5942 (e.g., a guiding hole 5942-1, a guiding hole 5942-2, aguiding hole 5942-3, a guide hole 5942-4, etc.) through the guidingtube. It should be noted that the guiding tube may be only an exemplaryembodiment of the acoustic route through which sound may propagate inthe open binaural earphone 5900. Those skilled in the art may use otheracoustic routes (e.g., an acoustic cavity, a resonant cavity, anacoustic hole, an acoustic slit, a tuning net, etc. or any combinationthereof) or other ways to make the sound propagate in the open binauralearphone 5900, which may be not limited herein.

In some embodiments, frequency-divided signals generated after the audiosignal is processed may have narrower frequency bands than a frequencyband of the audio signal. The frequency bands of the frequency-dividedsignals may be within the frequency band of the audio signal. Forexample, the frequency band of the audio signal may be from 10 Hz to 30kHz. The frequency bands of the frequency-divided signal may be 100 Hzto 200 Hz, which may be narrower than the frequency band of the audiosignal and within the frequency band of the audio signal. In someembodiments, a combination of the frequency bands of thefrequency-divided signals may cover the frequency band of the audiosignal. Additionally or alternatively, the combination of frequencybands of the frequency-divided signal may partially cover the frequencyband of the audio signal. In some embodiments, at least two of thefrequency-divided signals may have different frequency bands. As usedherein, the different frequency bands may refer to two frequency bandsthat have different frequency band center values and/or differentfrequency bandwidths. Optionally, each frequency-divided signal may havea characteristic frequency band that is different from that of otherfrequency-divided signals. That is, the frequency band of afrequency-divided signal may not overlap with the frequency bands ofother frequency-divided signals. Different frequency-divided signals mayhave the same frequency bandwidth or different frequency bandwidths. Insome embodiments, an overlap between the frequency bands of two adjacentfrequency-divided signals in a frequency domain may be avoided, therebyimproving the quality of the output sound. Among the generatedfrequency-divided signals, two frequency-divided signals with closecenter frequencies may be considered to be adjacent to each other in thefrequency domain. More descriptions regarding the frequency bands of apair of adjacent frequency-divided signals may be found elsewhere in thepresent disclosure. See, e.g., 63A and 63B and the relevant descriptionsthereof. In some embodiments, a low-frequency sound and a high-frequencysound actually output by the open binaural earphone 5900 may be affectedby various factors such as filtering characteristics of actual circuits,frequency characteristics of the transducers, frequency characteristicsof the acoustic routes, etc., and the low frequency sound and the highfrequency sound may have a certain overlap (e.g., an aliasing portion)in the frequency band near a frequency-divided point. It should beunderstood that the overlap may not affect an overall sound leakagereduction effect of the open binaural earphone 5900.

The housing 5910 may be an external structure of the open binauralearphone 5900, and a shape of the housing 5910 may be determinedaccording to a wearing type (e.g., ear-hook earphone, a headbandearphone, etc.) and a usage requirement, which is not limited herein.

The housing 5910 may include a hollow structure. The microphone 5920,the acoustic driver(s) 5930, the guiding tube, the baffle 5950, thecircuit board 5960, the Bluetooth module 5970, the power source module5980, etc., may be disposed in the hollow structure. As shown in FIG. 59and FIG. 60, the microphone 5920 and the acoustic driver(s) 5930 may bedisposed at a front end of the housing 5910. The circuit board 5960 maybe disposed in a middle portion of the housing 5910. The Bluetoothmodule 5970 and the power source module 5980 may be disposed at a rearend of the housing 5910. As used herein, the front end of the housing5910 refers to an end of the housing 5910 close to an ear canal of auser when the user wears the open binaural earphone, the rear end of thehousing 5910 refers to an end of the housing 5910 away from the earcanal of the user when the user wears the open binaural earphone, themiddle portion of the housing 5910 refers to a portion of the housingbetween the front end of the housing 5910 and the rear end of thehousing 5910.

In some embodiments, the microphone 5920, the acoustic driver(s) 5930,the guiding tube, the baffle 5950, the circuit board 5960, the Bluetoothmodule 5970, and the power source module 5980 may be disposed in anyother suitable positions of the housing 5910, which are not limitedherein. For example, the acoustic driver 5930-1, the microphone 5920,the circuit board 5960, etc., may be disposed at the front end of thehousing 5910, the Bluetooth module 5970 may be disposed in the middleportion of the housing 5910, and the acoustic driver 5930-2, the batterymodule 5980 may be disposed at the rear end of the housing 5910. Asanother example, the Bluetooth module 5970 and the power source module5980 may be disposed at the front end of the housing 5910, themicrophone 5920 and the circuit board 5960 may be disposed at the middleportion of the housing 5910, the acoustic driver 5930-1 and the acousticdriver 5930-2 may be disposed at the rear end of the housing 5910, andthe guiding hole may be disposed at the front end of the housing 5910through a guiding tube. It should be noted that the positions of themicrophone 5920, the acoustic driver(s) 5930, the guiding tube, thebaffle 5950, the circuit board 5960, the Bluetooth module 5970, and thepower source module 5980 in the housing 5910 may be determined based onan actual requirement for the open binaural earphone 5900, and thespecific positions of the components in the drawings are only forillustration purposes and do not limit the protection scope of thepresent disclosure. As shown in FIG. 61, the acoustic driver 5930-1 andthe acoustic driver 5930-2 may be separated by the baffle 5950.

In some embodiments, the housing 5910 may be integrally formed. In someembodiments, the housing 5910 may be assembled via a plugging manner, asnapping manner, etc. In some embodiments, the housing 5910 may be madeof a metal (e.g., copper, aluminum, titanium, gold, etc.), an alloy(e.g., aluminum alloy, a titanium alloy, etc.), a plastic (e.g.,polyethylene, polypropylene, epoxy resin, nylon, etc.), a fiber (e.g.,acetate fiber, propionate fiber, carbon fiber, etc.). In someembodiments, a protective cover may be disposed outside the housing5910. The protective cover may be made of a soft material with certainelasticity, such as a soft silica gel, a rubber, etc., to provide abetter touch sense for the user.

The surface of the housing 5910 may include one or more guiding holes,for example, the first guiding hole 5942-1, the second guiding hole5942-2, the third guiding hole 5942-3, and the fourth guiding hole5942-4. The open binaural earphone 5900 may transmit sound to the userthrough the air via the guiding holes. The acoustic driver(s) 5930 mayconvert the frequency-divided signals (e.g., an electrical signal) intoa voice signal, transmit the voice signal to the guiding holecorresponding to the acoustic driver through the guiding tubecorresponding to the guiding hole, and transmit the voice signal to theuser through the guiding hole. To illustrate the effect of the guidingholes on the housing 5910 on the sound output by the open binauralearphone 5900, the guiding holes on the open binaural earphone 5900 maybe regarded as sound sources for outputting sound (actually, the soundsource may be still an acoustic output device) considering that thesound may be regarded as propagating from the guiding holes in thepresent disclosure. For the convenience of description and the purposesof illustration, when the guiding hole on the open binaural earphone5900 has a relatively small size, each guiding hole may be regarded (orapproximately regarded) as a point sound source.

The microphone 5920 may be configured to receive an external voicesignal (e.g., a user's voice signal), and convert the received voicesignal into an electrical signal. The voice signal received by themicrophone 5920 may be processed to generate an audio signal (orfrequency-divided signals). The process of the voice signal may includefiltering, denoising, amplifying, smoothing and/or frequency division,or the like, or any combination thereof. The audio signal may be sent toan object or a device that is communicated with the open binauralearphone 5900 through other components (e.g., a Bluetooth assembly, awireless fidelity (WIFI) assembly, etc.) of the open binaural earphone5900.

The acoustic driver(s) 5930 may be configured to convert an inputelectrical signal into a voice signal and output the voice signal. Theconversion technique may include a technique of vibrating and generatinga sound. In some embodiments, the acoustic driver(s) 5930 may processthe received audio signal into frequency-divided signals due todifferent frequency responses of the acoustic drive(s) 5930, convert thefrequency-divided signals into voice signals with different frequencybands, and output the voice signals to the user who wears the openbinaural earphone 5900. In some embodiments, the acoustic driver(s) 5930may directly receive frequency-divided signals with different frequencybands, convert the received frequency-divided signals into voicesignals, and output the voice signals to the user who wears the openbinaural earphones 5900. In some embodiments, the acoustic driver(s)5930 may include at least two loudspeaker units (or transducers). Forexample, only two loudspeaker units are shown in FIG. 59, FIG. 60, andFIG. 61 (i.e., a first loudspeaker unit 5930-1 and a second loudspeakerunit 5930-2). The first loudspeaker unit 5930-1 may correspond to alow-frequency signal, and the second loudspeaker unit 5930-2 maycorrespond to a high-frequency signal. In some embodiments, the acousticdriver(s) 5930 may include an air conductive loudspeaker, a boneconductive loudspeaker, a hydro-acoustic transducer, an ultrasonictransducer, or the like, or any combination thereof. In someembodiments, the acoustic driver(s) 5930 may include a moving coilloudspeaker, a moving iron loudspeaker, a piezoelectric loudspeaker, anelectrostatic loudspeaker, a magnetostrictive loudspeaker, a balancedarmature loudspeaker, or the like, or any combination thereof. In someembodiments, the loudspeaker units may have the same frequency responsecharacteristic. In some embodiments, the loudspeaker units may havedifferent frequency response characteristics.

It may be noted that a specific loudspeaker unit corresponding to aspecific frequency-divided signal may indicate that a frequency band ofthe frequency-divided signal input to the specific loudspeaker unit maybe the same as the frequency band of the specific frequency-dividedsignal, may indicate that the specific loudspeaker unit may generate thespecific voice signal, or may indicate that the frequency band of thespecific voice signal transmitted through the guiding hole after thatthe specific voice signal processed and transmitted by the specificloudspeaker unit may be the same as that of the specificfrequency-divided signal.

Each loudspeaker unit may be configured to convert the input electricalsignals (e.g., different frequency-divided signals) into voice signalsusing the technique of vibrating and generating the sound and output thevoice signals. In some embodiments, each loudspeaker unit may correspondto two guiding holes. Each loudspeaker unit may output a set of voicesignals with opposite phases and the same intensity, which may berespectively transmitted to the user through the guiding tube and thecorresponding two guiding holes 5942. For example, the loudspeaker unitmay include a vibration diaphragm, which may be driven by an electricsignal to generate vibration, and a front side and a rear side of thevibration diaphragm may simultaneously output a positive phase sound anda reverse-phase sound. In some embodiments, by setting positions of theguiding holes, the positive phase sound and the reverse phase sound mayhave the same or similar phase at a hearing position and may besuperimposed at the hearing position (i.e., the near-field such as acenter position of an ear hole of a human ear). In addition, thepositive phase sound and the reverse phase sound in the far-field mayhave different phases (e.g., a common leakage point in the surroundingenvironment) and may be canceled out in the far-field, thereby improvinga volume of a sound in the near-field and reducing sound leakage in thefar-field. In some embodiments, guiding holes corresponding to the sameloudspeaker unit may be referred to as a dual-point sound source. Forexample, the first guiding hole 5942-1 and the second guiding hole5942-2 corresponding to the loudspeaker unit 5930-1 may be referred toas a dual-point sound source, and/or the third guiding hole 5942-2 andthe fourth guiding hole 5942-3 corresponding to the loudspeaker unit5930-2 may be referred to as a dual-point sound source. In someembodiments, frequency bands and amplitudes of frequency-divided signalstransmitted from guiding holes of the dual-point sound source may be thesame, respectively, and phases thereof may be different (e.g., thephases may be opposite). In some embodiments, the frequency bands of thefrequency-divided signals transmitted from the guiding holes in thedual-point sound source may be the same, and the phases may be the same.In some embodiments, a loudspeaker unit may correspond to one singleguiding hole. That is, the loudspeaker unit may correspond to a singlepoint sound source. In other words, the loudspeaker unit may output onlyone frequency-divided signal. For example, a side of the loudspeakerunit 5930-1 facing the guiding hole 5942-2 may be sealed. A dual-pointsound source may be constructed by two loudspeaker units (i.e., twosingle point sound sources). For example, two balanced armatureloudspeakers may be configured to construct a high-frequency dual-pointsound source (i.e., the dual-point sound source corresponding to ahigh-frequency signal). In some embodiments, a frequency, a phase, anamplitude, and other parameters of the frequency-divided signalcorresponding to each point sound source in each set of dual-point soundsources may be adjusted individually. For example, the frequency of eachpoint sound source in each set of dual-point sound sources may be thesame, and the phase may be the same or different. As another example,the frequency of each point sound source in each set of dual-point soundsources may be the same, and the amplitude may be the same or different.

In some embodiments, the higher the frequency band of thefrequency-divided signal corresponding to the loudspeaker unit is, theshorter a distance between two guiding holes corresponding to theloudspeaker unit may be. For example, the first loudspeaker unit 5930-1may be configured to output low-frequency signals, and the secondloudspeaker unit 5930-2 may be configured to output high-frequencysignals. A distance between the first guiding hole 5942-1 and the secondguiding hole 5942-2 corresponding to the first loudspeaker unit 5930-1may be greater than a distance between the third guiding hole 5942-3 andthe fourth guiding hole 5942-4 corresponding to the second loudspeakerunit 5930-2. By setting the distance of the guiding holes correspondingto the loudspeaker units in this manner, the sound leakage of the openbinaural earphone 5900 may be reduced. It may be because when thedistance between the two point sound sources of the dual-point soundsource is constant, the leakage sound generated by the dual-point soundsource may be increased with the increment of the audio frequency, andthe leakage reduction may be reduced with the increment of the audiofrequency. When the audio frequency is greater than a certain value, theleakage sound of the dual-point sound source may be more than that ofthe single-point sound source, and the certain value may be an upperlimit frequency at which the dual-point sound source may reduce thesound leakage. More descriptions regarding the distance, the dual-pointsound source, and the upper limit frequency of sound leakage may befound elsewhere in the present disclosure. See, e.g., FIG. 2 and FIG. 3and the relevant descriptions thereof. For different frequency-dividedsignals, by setting a plurality of sets of dual-point sound sources thepoint sound sources in each of which may be with different distances, astronger leakage reduction ability than that of the single-point soundsource may be obtained. For example, the audio signal may be dividedinto three frequency bands such as a low frequency band, a mediumfrequency band, and a high frequency band. A low-frequency dual-pointsound source, a mid-frequency dual-point sound source, and ahigh-frequency dual-point sound source may be generated by settingdifferent distances between two point sound sources of each of thedual-point sound sources. The low-frequency dual-point sound source mayhave a relatively large distance than the high-frequency dual-pointsound source and mid-frequency dual-point sound source, themid-frequency dual-point sound source may have a middle distance betweenthe low-frequency dual-point sound source and high-frequency dual-pointsound source, and the high-frequency dual-point sound source may have arelatively small distance than the low-frequency dual-point sound sourceand mid-frequency dual-point sound source. In the low-frequency band,due to the increment of the volume of the sound is greater than theincrement of the volume of the leakage sound when the distance betweenthe sound sources is enlarged, a sound with a relatively high volume maybe output in the low-frequency band. Due to the sound leakage of thedual-point sound source in the low-frequency band is relatively small,when the distance between the sound sources is enlarged, the soundleakage may be slightly increased and kept at a relatively low level. Inthe high-frequency band, a relatively low upper limit frequency ofhigh-frequency leakage reduction may be improved and a relatively narrowaudio frequency range of the leakage reduction may be enlarged bydecreasing the distance between the sound sources. The open binauralearphone 5900 may have a relatively strong sound leakage reductioneffect in higher-frequency bands, which may satisfy the requirements ofopen binaural.

In some embodiments, the acoustic driver(s) 5930 may include the firstloudspeaker unit 5930-1 and the second loudspeaker unit 5930-2, thefirst loudspeaker unit 5930-1 may correspond to a low-frequency signal,and the second loudspeaker unit 5930-2 may correspond to ahigh-frequency signal. In some embodiments, the frequency division pointbetween the low frequency and the high frequency may be between 600 Hzand 1.2 kHz. In some embodiments, the first loudspeaker unit 5930-1 maycorrespond to the guiding hole 5942-1 and the guiding hole 5942-2, andthe second loudspeaker unit 5930-2 may correspond to the guiding hole5942-3 and the guiding hole 5942-4. A distance d_(l) between the guidinghole 5942-1 and the guiding hole 5942-2 and the distance d_(h) betweenthe guiding hole 5942-3 and the guiding hole 5942-4 may be various.Merely by way of example, d_(l) may be not larger than 40 millimeters,for example, in the range of 20 millimeters-40 millimeters, and d_(h)may be not larger than 12 millimeters and d_(l) is larger than d_(h). Insome embodiments, d_(l) may be not less than 12 millimeters, and d_(h)may be not greater than 7 millimeters, for example, in the range of 3millimeters-7 millimeters. In some embodiments, d_(l) may be 30millimeters, and d_(h) may be 5 millimeters. As another example, d_(l)may be at least twice of d_(h). In some embodiments, d_(l) may be atleast 3 times of d_(h). In some embodiments, d_(l) may be at least 5times of d_(h). In some embodiments, a range of d₁/d_(h) may be 2-10,2.5-9.5, 3-9, 3.5-8.5, 4-8, 4.5-7.5, 5-7, 5.5-6.5, 6, etc.

In some embodiments, each set of dual-point sound sources may include anear-ear point sound source and a far-ear point sound source. Forexample, when the user wears the open binaural earphones 5900, the firstguiding hole 5942-1 may be closer to the ear hole than the secondguiding hole 5942-2, and the third guiding hole 5942-3 may be closer tothe ear hole than the fourth guiding hole 5942-4, and accordingly, thefirst guiding hole 5942-1 and the third guiding hole 5942-3 may bereferred to as the near-ear point sound sources, the second guiding hole5942-2 and the fourth guiding hole 5942-4 may be referred to as thefar-ear point sound sources. In some embodiments, a distance L betweenthe first guiding hole 5942-1 and the third guiding hole 5942-3 may benot greater than 20 millimeters, 18 millimeters, 16 millimeters, 14millimeters, 12 millimeters, 10 millimeters, 9 millimeters, 8millimeters, 7 millimeters, 6 millimeters, 5 millimeters, 4 millimeters,3 millimeters, 2 millimeters, 1 millimeter, etc. In some embodiments,the distance L may be equal to zero. When the distance L is equal to 0,the near-ear point sound sources in each set of dual-point sound sourcesmay be combined into one guiding hole and configured as a main guidinghole to transmit sound to the ear hole of the user. For example, thefirst guiding hole 5942-1 and the third guiding hole 5942-3 may becombined into one guiding hole (e.g., a guiding hole 5942-5 in FIG. 62).In some embodiments, at least a portion of at least one guiding hole mayface the user's ear. In this case, the sound from the guiding hole maybe transmitted to the user's ear hole (as shown in FIG. 62).

In some embodiments, a shape of the guiding hole may include astrip-shape, a circle, an ellipse, a square, a trapezoid, a roundedquadrilateral, a triangle, an irregular shape, or the like, or anycombination thereof. In some embodiments, the shapes of the guidingholes may be the same or different. For example, a shape of the firstguiding hole 5942-1 and a shape of the third guiding hole 5942-3 may becircular, and a shape of the second guiding hole 5942-2 and a shape ofthe fourth guiding hole 5942-4 may be oval. As another example, theshape of the first guiding hole 5942-1 may be strip-shaped, the shape ofthe second guiding hole 5942-2 may be an oval, the shape of the thirdguiding hole 5942-3 may be a circle, and the shape of the fourth guidingholes 5942-4 may be triangular. As yet another example, the shapes ofthe first guiding hole 5942-1, the second guiding hole 5942-2, the thirdguiding hole 5942-3, and the fourth guiding hole 5942-4 may be allstrip-shaped.

In some embodiments, apertures or sizes of guiding holes correspondingto different loudspeaker units may be the same or different. In someembodiments, when the sizes of the guiding holes are different, thevolumes of the corresponding sound and/or leakage sound may bedifferent. In some embodiments, by setting a near-to-far aperture ratio(i.e., the ratio of the aperture of a guiding hole near an ear, i.e., anear-ear point sound source to the aperture of a guiding hole far awaythe ear, i.e., far-ear point sound source), the dual-point sound sourcemay obtain relatively strong leakage reduction capability. In someembodiments, the higher a frequency band of a frequency-divided signalcorresponding to a dual-point sound source is, the smaller thenear-to-far aperture ratio may be. As the frequency band of thefrequency-divided signal corresponding to the dual-point sound sourcebecomes higher, the aperture of the near-ear point sound source and theaperture of the far-ear point sound source may gradually become thesame. For example, for the dual-point sound source corresponding tolow-frequency signals, the aperture of the near-ear point sound sourcemay be greater than the aperture of the far-ear point sound source. Forthe dual-point sound source corresponding to high-frequency signals, theaperture of the near-ear point sound source may be the same as orsimilar to that of the far-ear point sound source.

In some embodiments, the near-to-far aperture ratio of the dual-pointsound source corresponding to the low-frequency signals may be not lessthan 1, 5, 10, 15, 20, 25, 30, etc. In some embodiments, the near-to-faraperture ratio of a dual-point sound source corresponding to thehigh-frequency signals may be not greater than 10, 8, 6, 4, 3, 2, etc.In some embodiments, the near-to-far aperture ratio may be equal to 1.

In some embodiments, by adjusting the positions of different guidingholes, the user may obtain different listening effects. Moredescriptions regarding the positions of the guiding holes and a hearingposition may be found elsewhere in the present disclosure (e.g., FIG. 28and the relevant descriptions thereof). In some embodiments, when theuser wears the open binaural earphone 5900, a distance D_(n) between acenter point of the near-ear point sound source of each set ofdual-point sound source and a center point of the user's ear hole 6210may be no more than 10 centimeters, 9 centimeters, 8 centimeters, 7centimeters, 6 centimeters, 5 centimeters, 4 centimeters, 3 centimeters,2.5 centimeters, 2 centimeters, 1.5 centimeters, 1 centimeters, 0.5centimeters, 0.4 centimeters, 0.3 centimeters, 0.2 centimeters, 0.1centimeters, etc., thereby improving the user's listening experience.

In some embodiments, the open binaural earphone 5900 may include alow-frequency loudspeaker unit and a high-frequency loudspeaker unit,and the near-ear guiding hole corresponding to the low-frequencyloudspeaker unit may be combined with the near-ear guiding holecorresponding to the high-frequency loudspeaker unit into one singleguiding hole. For example, as shown in FIG. 62, the first guiding hole5942-1 and the third guiding hole 5942-3 may be combined into theguiding hole 5942-5. In some embodiments, one end of the guiding hole5942-5 may be disposed on an end surface 5912, and the other end of theguiding hole 5942-5 may be disposed on an end surface 5914. When theuser wears the open binaural earphones 5900, the first guiding hole5942-1 and the third guiding hole 5942-3 (i.e., near-ear point soundsources) may face the user's ear hole, and the user may hear the sound(i.e., hearing sound) with a relatively high volume. In someembodiments, the second guiding hole 5942-2 may be disposed on the endsurface 5912. The fourth guiding hole 5942-4 may be disposed on an endsurface 5916. In some embodiments, the first guiding hole 5942-1, thesecond guiding hole 5942-2, the third guiding hole 5942-3, and thefourth guiding hole 5942-4 may all be disposed on the end surface 5912(or the end surface 5916). In some embodiments, the third guiding hole5942-3 may be disposed on the end surface 5912 and the fourth guidinghole 5942-4 may be disposed on a surface opposite to the end surface5912. In some embodiments, as shown in FIG. 59, the first guiding hole5942-1 and the second guiding hole 5942-2 may be disposed at anyposition of the front end of the housing 5910 (e.g., the end face 5912,the end face 5914, the end face 5916, etc.), the third guiding hole5942-3 and the fourth guiding hole 5942-4 may be disposed at anyposition of the rear end of the housing 5910. In some embodiments, thefirst guiding hole 5942-1 and the third guiding hole 5942-3 may bedisposed at the front end of the housing 5910, and the second guidinghole 5942-2 and the fourth guiding hole 5942-4 may be disposed at therear end of the housing 5910. In some embodiments, when the user wearsthe open binaural earphone 5900, a distance D between a center point ofthe guiding hole 5942-5 and a center point of the ear hole close to thecenter point of the guiding hole 5942-5 may be not greater than 10centimeters, 9 centimeters, 8 centimeters, 7 centimeters, 6 centimeters,5 centimeters, 4 centimeters, 3 centimeters, 2.5 centimeters, 2centimeters, 1.5 centimeters, 1 centimeters, 0.5 centimeters, 0.4centimeters, 0.3 centimeters, 0.2 centimeters, 0.1 centimeters, etc.

In some embodiments, a baffle may be disposed between two point soundsources of a dual-point sound source, and the volume of the near-fieldsound may be significantly increased under the condition that the volumeof the far-field sound leakage is not increased significantly, therebyimproving the user's listening experience. More descriptions regardingthe baffle between the two point sound sources of a dual-point soundsource may be found elsewhere in the present disclosure. See, e.g., FIG.11 to FIG. 34 and the relevant descriptions thereof.

In some embodiments, a low-frequency dual-point sound source may includea guiding hole disposed at a near-ear point (i.e., a near-ear guidinghole or near-ear point sound source), and a guiding hole at a far-earpoint may be disposed at a rear end of the housing 5910 (i.e., a far-earguiding hole or far-ear point sound source). When the user wears theopen binaural earphone 5900, the near-ear point sound source and thefar-ear point sound source may be separated by the user's auricle. Onthis occasion, the auricle may act as a baffle, thereby significantlyincreasing the volume of the near-field sound, and improving the user'slistening experience.

In some embodiments, internal friction or viscous force of a medium inthe guiding tube may affect sound propagation, and a diameter of theguiding tube may be not too small, otherwise, it may cause sound lossand reduce output volume. However, when the diameter of a guiding tubeis too great, when the transmitted sound is greater than a certainfrequency, high-order waves may be generated in the guiding tube. Toavoid the generation of the high-order waves, the diameter of theguiding tube may be determined reasonably. In some embodiments, thediameter of the guiding tube may be 0.5 millimeters-10 millimeters, 0.5millimeters-9 millimeters, 0.7 millimeters-8 millimeters, 0.9millimeters-7.5 millimeters, 1 millimeters-7 millimeters, 1.5millimeters-6.5 millimeters, 2 millimeters-6 millimeters, 2.5millimeters-5.5 millimeters, 3 millimeters-5 millimeters, 3.5millimeters-4.5 millimeters, 3.7 millimeters-4.2 millimeters, etc.

In some embodiments, a radiation impedance of a guiding tube and aradiation impedance of a nozzle (also referred to as a guiding hole) mayinteract with each other, which may cause a sound with a specificfrequency to form a standing wave in the guiding tube, and one or morepeaks/valleys may be formed at one or more frequencies of an outputsound, thereby affecting the quality of the output sound. Generally, thelonger a length of the guiding tube is, the lower the frequency offorming the one or more peaks/valleys is, and the greater the count ofthe one or more peaks/valleys may be. In some embodiments, the length ofthe guiding tube may be not greater than 300 millimeters. In someembodiments, the length of the guiding tube may be not greater than 250millimeters, 200 millimeters, 150 millimeters, 100 millimeters, 50millimeters, 30 millimeters, 20 millimeters, 10 millimeters, etc. Insome embodiments, an impedance matching layer may be disposed at theguiding hole to reduce the effect of the one or more peaks/valleys. Insome embodiments, a length-to-diameter ratio (i.e., a ratio of thelength to the diameter) of the guiding tube may affect the soundgenerated in the guiding tube. The effect of the length-to-diameter maybe the same as or similar to the effect of low-pass filtering and theeffect of damping, which may attenuate the volume, and the attenuationof a volume of a high-frequency sound may be greater than theattenuation of a volume of a low-frequency sound. To avoid that theattenuation affects a hearing sound, in some embodiments, the length todiameter ratio of the guiding tube may be not greater than 200, 180,160, 150, 130, 110, 80, 50, 30, 10, etc.

In some embodiments, parameters (e.g., a length, a diameter, alength-to-diameter ratio, etc.) of each guiding tube may be the same ordifferent. For example, a length of the first guiding tube 5940-1 may be5 millimeters, and a length of the second guiding tube 5940-2 may be 30millimeters. As another example, the lengths of the first guiding tube5940-1 and the third guiding tube 5940-3 may both be 5 millimeters.

In some embodiments, the phases of frequency-divided signalscorresponding to point sound sources may be different, and the volumesof the hearing sound and the leakage sound may be different. Therefore,different output effects may be achieved by adjusting the phases of thepoint sound sources. In some embodiments, to reduce the far-fieldleakage sound of the open binaural earphone 5900, the acoustic driver5930-1 may generate low-frequency sounds with the same (or substantiallythe same) amplitude and opposite (or substantially opposite) phases atthe first guiding hole 5942-1 and the second guiding hole 5942-2,respectively, and the acoustic driver 5930-2 may generate high-frequencysounds with the same (or substantially the same) amplitude and opposite(or substantially opposite) phases at the first guiding hole 5942-3 andthe second guiding hole 5942-4, respectively. In some embodiments, thehigher the frequency bands of the frequency-divided signalscorresponding to the dual-point sound source is, the greater a phasedifference between the frequency-divided signals may be. For example, inthe dual-point sound source including two loudspeaker units, for adual-point sound source corresponding to low-frequency signals, thephase difference between the low-frequency signals transmitted from thedual-point sound source may be adjusted to be equal (or substantiallyequal) to 0°. For a dual-point sound source corresponding tohigh-frequency signals, the phase difference between the high-frequencysignals transmitted from the dual-point sound source may be adjusted tobe equal (or substantially equal) to 180°. In some embodiments, thephase of the dual-point sound source may be adjusted, and the phasedifference of sounds generated by the dual-point sound source at thenear-field position (or a center point of the ear hole) may be equal (orsubstantially equal) to 0°, and the phase difference between the soundat the far-field position may be equal (or substantially equal) to 180°.In some embodiments, a phase difference of sounds output by two pointsound sources of the dual-point sound source may be equal to 5°, 10°,20°, 50°, 70°, 90°, 100°, 120°, 130°, 150°, 170°, 175°, 180°, etc.

The circuit board 5960 may be configured to integrate one or morecomponents to realize various functions. For example, a frequencydivision processing unit may be integrated into the circuit board torealize the frequency division function on audio signals. As anotherexample, a signal processing unit may be integrated into the circuitboard to adjust the phases and/or amplitudes of the audio signals. TheBluetooth module 5970 may be configured to communicate the open binauralearphone 5900 with an external device. For example, the open binauralearphone 5900 may be communicated with an external audio device throughBluetooth module 5970. In some embodiments, the Bluetooth module 5970may be integrated on the circuit board 5960. The power source module5980 may be configured to provide power to the one or more components ofthe open binaural earphone 5900. In some embodiments, the power sourcemodule 5980 may include an accumulator, a dry battery, a lithiumbattery, a Daniell battery, a fuel battery, or the like. Othercomponents such as the circuit board 5960, the Bluetooth unit 5970, andthe power source module 5980 of the open binaural earphone 5900 may bereferred to the settings of general earphones in the prior art, whichare not repeated herein.

It should be noted that the descriptions of the open binaural earphone5900 may be intended to be illustrative, which does not limit the scopeof the present disclosure. For example, the open binaural earphone 5900may include one or more additional components, and one or morecomponents of the open binaural earphone 5900 described above may beomitted. Merely by way of example, a feedback microphone may be added tothe open binaural earphone 5900. The feedback microphone may beconfigured to reduce a residual noise (e.g., a circuit current noise).As another example, the baffle 5950 may be omitted. As yet anotherexample, one or more buttons (e.g., a volume increase button, a volumedecrease button, a power button, a Bluetooth switch button, etc.) may bedisposed on the housing 5910. As yet another example, the open binauralearphone 5900 may be connected with a user terminal through theBluetooth module 5970. The user terminal may display a controlinterface, and the user may issue a control instruction through thecontrol interface, for example, increasing or decreasing the volume,etc. The control signal may be received by the Bluetooth module 5970 andrealize the control of the open binaural earphone 5900. In someembodiments, the Bluetooth module 5970 may be omitted. The open binauralearphone 5900 may communicate with an external device through a datacable.

FIG. 63A is a schematic diagram illustrating an exemplary frequencyresponse 6310 of the first loudspeaker unit 5930-1 and an exemplaryfrequency response 6320 of the second loudspeaker unit 5930-2 as shownin FIG. 59 according to some embodiments of the present disclosure. FIG.63B is a schematic diagram illustrating the exemplary frequency response6310 of the first loudspeaker unit 5930-1 and another exemplaryfrequency response 6330 of the second loudspeaker unit 5930-2 as shownin FIG. 59 according to some embodiments of the present disclosure. Thefirst loudspeaker unit 5930-1 may be configured to process an audiosignal to generate a first frequency-divided signal. The secondloudspeaker unit 5930-2 may be configured to process an audio signal togenerate a second frequency-divided signal. In the frequency-dividedsignals, the second frequency-divided signal may be adjacent to thefirst frequency-divided signal in a frequency domain.

In some embodiments, the frequency response of the first loudspeakerunit 5930-1 and the frequency response of the second loudspeaker unit5930-2 may have the same frequency bandwidth. For example, as shown inFIG. 63 A, the frequency response 6310 of the first loudspeaker unit5930-1 may have a low half power point f1, a high half power point f2,and a center frequency f3. As used herein, a half-power point of acertain frequency response may refer to a frequency point with aspecific power suppression (e.g., −3 dB). The frequency bandwidth of thefrequency response 6310 may be equal to a difference between the highhalf power point f2 and the low half power point f1. The frequencyresponse 6320 of the second loudspeaker unit 5930-2 may have a low halfpower point f2, a high half power point f4, and a center frequency f5.The frequency bandwidth of the frequency response 6320 may be equal to adifference between the high half power point f4 and the low half powerpoint f2. The frequency bandwidth of the first loudspeaker unit 5930-1may be equal to the frequency bandwidth of the second loudspeaker unit5930-2.

In some embodiments, the frequency response of the first loudspeakerunit 5930-1 and the frequency response of the second loudspeaker unit5930-2 may have different frequency bandwidths. For example, as shown inFIG. 63B, the frequency response 6330 of the second loudspeaker unit5930-2 may have a low half power point f2, a high half power point f7(which is greater than f4), and a center frequency f6. The frequencybandwidth of the frequency response 6330 of the second loudspeaker unit5930-2 may be equal to a difference between the high half power point f7and the low half power point f2, and the difference (i.e., the frequencybandwidth of the frequency response 6330 of the second loudspeaker unit5930-2) may be greater than the frequency bandwidth of the frequencyresponse 6310 of the first loudspeaker unit 5930-1.

In some embodiments, the frequency response of the first loudspeakerunit 5930-1 and the frequency response of the second loudspeaker unit5930-2 may intersect at a specific frequency point. The intersection ofthe frequency responses may indicate that an overlap between the firstfrequency response and the second frequency response. On an idealoccasion, the frequency response of the first loudspeaker unit 5930-1may not overlap with the frequency response of the second loudspeakerunit 5930-2. Actually, the frequency response of the first loudspeakerunit 5930-1 may overlap with the frequency response of the secondloudspeaker unit 5930-2, which may cause an interference range betweenthe first frequency-divided signal and the second frequency-dividedsignal, and affect the quality of the first frequency-divided signal andthe second frequency-divided signal. For example, the larger theoverlapping range is, the larger the interference range may be, and thelower the quality of the first frequency-divided signal and the secondfrequency-divided signal may be.

In some embodiments, the specific frequency point at which the frequencyresponse of the first loudspeaker unit 5930-1 and the frequency responseof the second loudspeaker unit 5930-2 intersect may be close to the halfpower point of the frequency response of the first loudspeaker unit5930-1 and/or the half power point of the frequency response of thesecond loudspeaker unit 5930-2. Taking FIG. 63A as an example, thefrequency response 6310 and the frequency response 6320 intersect at thehigh half power point f2 of the frequency response 6310, and the highhalf power point f2 may be the low half power point of the frequencyresponse 6320. As used herein, when a power level difference between thefrequency point and the half-power point is not greater than a threshold(e.g., 2 dB), it may be considered that the frequency point is close tothe half power point. In this case, relatively little energy loss orrepetition may be formed in the frequency response of the firstloudspeaker unit 5930-1 and the frequency response of the secondloudspeaker unit 5930-2, which may cause an overlapping range betweenthe frequency response of the first loudspeaker unit 5930-1 and thefrequency response of the second loudspeaker unit 5930-2. Merely by wayof example, assuming that the half power point is −3 dB and thethreshold is −2 dB, when the frequency responses intersect at afrequency point with a power level greater than −5 dB and/or less than−1 dB, the overlapping range may be considered to be relatively small.In some embodiments, the center frequency and/or the bandwidth of thefrequency response of the first loudspeaker unit 5930-1 and the centerfrequency and/or the bandwidth of the frequency response of the secondloudspeaker unit 5930-2 may be adjusted to generate a relatively narrowor an required overlapping range between the frequency response of thefirst loudspeaker unit 5930-1 and the frequency response of the secondloudspeaker unit 5930-2, thereby avoiding the overlapping between thefrequency band of the first frequency-divided signal and the frequencyband of the second frequency-divided signal.

FIG. 64 is a schematic diagram illustrating an exemplary open binauralheadphone 6400 according to some embodiments of the present disclosure.As shown in FIG. 64, the open binaural headphone 6400 may be called aheadband headphone. The open binaural headphone 6400 may have a similarconfiguration to the open binaural earphone 5900. For example, the openbinaural headphone 6400 may include a housing 6410, a microphone, one ormore acoustic drivers (e.g., one or more loudspeaker units), one or moreguiding tube corresponding to the acoustic driver(s), a baffle, acircuit board, a Bluetooth module, and a power source module. Thehousing 6410 may include a first guiding hole 6420-1, a second guidinghole 6420-2, a third guiding hole 6420-3, and a fourth guiding hole6420-4 corresponding to the acoustic driver(s). As shown in FIG. 64, thefirst guiding hole 6420-1 and the second guiding hole 6420-2 of the openbinaural headphone 6400 may correspond to a low-frequency loudspeakerunit, and the third guiding hole 6420-3 and the fourth guiding hole6420-4 may correspond to a high-frequency loudspeaker unit. In someembodiments, the first guiding hole 6420-1 may be disposed on an endsurface 6414 of the open binaural headphone 6400, the second guidinghole 6420-2 may be disposed on an end surface 6412 of the open binauralheadphone 6400 and located at the top of the housing 6410, and the thirdguiding hole 6420-3 and the fourth guiding hole 6420-4 may both bedisposed on the end surface 6412 and located at a middle portion of aleft end and/or a right end of the housing 6410. More descriptions ofthe open binaural headphone 6400 may be combined with the description ofthe open binaural earphone 5900, which may be not repeated herein. Forexample, when a user wears the open binaural headphone 6400, a distancebetween a center point of the first guiding hole 6420-1 and a centerpoint of a user's ear hole close to the center point of the firstguiding hole 6420-1 may be the same as the distance between the centerpoint of the guiding hole 5942-5 of the open binaural earphone 5900 andthe center point of a user's ear hole close to the center point of theguiding hole 5942-5. As another example, shapes and/or sizes of thefirst guiding hole 6420-1, the second guiding hole 6420-2, the thirdguiding hole 6420-3, and the fourth guiding hole 6420-4 of the openbinaural earphone 6400 may be the same as that of the first guiding hole5942-1, the second guiding hole 5942-2, the third guiding hole 5942-3,and the fourth guiding hole 5942-4 of the open binaural earphone 5900,respectively.

It should be noted that an ear-hook earphone may be taken as an exampleto describe the open binaural earphone according to some embodiments ofthe present disclosure, which is not limited that the principle isapplied to other open binaural headphones. The positions of the acousticdriver(s), the guiding tubes, and the guiding holes of the open binauralheadphone disclosed in the present disclosure may be only examples,which does not limit the scope of the present disclosure. Varioussubstitutions, modifications, and changes may be obvious to thoseskilled in the art. For example, the open binaural earphone 5900 mayinclude three loudspeaker units, and the three loudspeaker units maycorrespond to a voice signal in a low-frequency band, a voice signal ina mid-frequency band, and a voice signal in a high-frequency band (i.e.,a low-frequency loudspeaker unit, a mid-frequency loudspeaker unit, anda high-frequency loudspeaker unit), respectively. The low-frequencyloudspeaker unit, the corresponding guiding tube, and the correspondingguiding holes may be disposed at the front end of the housing, themid-frequency loudspeaker unit, the corresponding guiding tube, and thecorresponding guiding holes may be disposed in a middle portion of thehousing, the high-frequency loudspeaker unit, the corresponding guidingtube, and the corresponding guiding holes may be disposed at the rearend of the housing. As another example, the low-frequency loudspeakerunit, the mid-frequency loudspeaker unit, and the high-frequencyloudspeaker unit may be disposed at the rear end of the housing, and theguiding holes may be disposed at the front end of the housing throughthe guiding tube corresponding to the loudspeaker unit. As yet anotherexample, the high-frequency loudspeaker unit and/or the low-frequencyloudspeaker unit of the open binaural headphone 6400 may correspond tofour guiding tubes and four guiding holes. The four guiding holes may bedisposed in pairs on a left and a right side of the housing 6410 as alow-frequency dual-point sound source for the left and right ears of theuser.

The beneficial effects of the embodiments of the present disclosure mayinclude but be not limited to the following. (1) The sound withdifferent frequency bands may be output by setting a high-frequencydual-point sound source and a low-frequency dual-point sound source,thereby improving the quality of the output sound; (2) The leakagereduction performance of an acoustic output device may be improved bysetting that two point sound sources of the dual-point sound source withdifferent distances, thereby satisfying requirements of an open binauralacoustic output device; (3) A baffle is set to increase the lengthdifference between acoustic routes from the two point sound sources of adual-point sound source to a hearing sound position, thereby increasingthe volume of the hearing sound in the near field, reducing the volumeof the leakage sound in the far-field, and improving the quality of theoutput sound of the open binaural acoustic output device; (4) An opencoupling of an acoustic output device and an ear hole is realized,thereby avoiding hearing loss of an ear, and avoiding safety hazardcaused by that the user wears a conventional earphone for a long time;(5) The acoustic output device is optimized in different product forms(e.g., glasses, an earphones, a headphone, etc.) from variousperspectives, for example, a microphone noise reduction system used toimprove the sound reception effect, an FPC used to simplify the wiringof the acoustic output device and reduce the mutual interference betweenwires, a Bluetooth technique and a button technique used to improve theportability and operability of the acoustic output devices, or the like,or any combination thereof. It should be noted that differentembodiments may have different beneficial effects. In differentembodiments, the possible beneficial effects may be any one or acombination of the beneficial effects described above, or any otherbeneficial effects.

What is claimed is:
 1. A pair of glasses, comprising a frame, one ormore lenses, and one or more temples, wherein the glasses furtherinclude: at least one low-frequency acoustic driver configured to outputsounds from at least two first guiding holes; at least onehigh-frequency acoustic driver configured to output sounds from at leasttwo second guiding holes, wherein a first distance is between the twofirst guiding holes, a second distance is between the two second guidingholes, the first distance exceeds the second distance, and the firstdistance is in a range of 20 millimeters-40 millimeters; and acontroller configured to direct the low-frequency acoustic driver tooutput the sounds in a first frequency range and direct thehigh-frequency acoustic driver to output the sounds in a secondfrequency range, the second frequency range including one or morefrequencies higher than one or more frequencies in the first frequencyrange.
 2. The glasses of claim 1, wherein the second distance is in arange of 3 millimeters-7 millimeters.
 3. The glasses of claim 1, whereinthe first distance is at least twice of the second distance.
 4. Theglasses of claim 1, wherein the first frequency range includesfrequencies lower than 650 Hz, and the second frequency range includesfrequencies higher than 1000 Hz.
 5. The glasses of claim 1, wherein thefirst frequency range overlaps with the second frequency range.
 6. Theglasses of claim 1, wherein the controller includes an electronicfrequency division module configured to divide an audio source signal togenerate a low-frequency signal corresponding to the first frequencyrange and a high-frequency signal corresponding to the second frequencyrange, the low-frequency signal driving the at least one low-frequencyacoustic driver to generate the sounds, and the high-frequency signaldriving the at least one high-frequency acoustic driver to generate thesounds.
 7. The glasses of claim 6, wherein the electronic frequencydivision module includes at least one of a passive filter, an activefilter, an analog filter, or a digital filter.
 8. The glasses of claim1, wherein the at least one low-frequency acoustic driver includes afirst transducer, the at least one high-frequency acoustic driverincludes a second transducer, and the first transducer and the secondtransducer have different frequency response characteristics.
 9. Theglasses of claim 8, wherein the first transducer includes alow-frequency loudspeaker, and the second transducer includes ahigh-frequency loudspeaker.
 10. The glasses of claim 1, wherein at leasttwo first acoustic routes are formed between the at least onelow-frequency acoustic driver and the at least two first guiding holes,at least two second acoustic routes are formed between the at least onehigh-frequency acoustic driver and the at least two second guidingholes, and the at least two first acoustic routes and the at least twosecond acoustic routes have different frequency selectioncharacteristics.
 11. The glasses of claim 10, wherein each of the atleast two first acoustic routes includes an acoustic resistancematerial, and an acoustic impedance of the acoustic resistance materialis in a range from 5MKS Rayleigh to 500MKS Rayleigh.
 12. The glasses ofclaim 1, further comprising: a supporting structure configured tosupport the at least one high-frequency acoustic driver and the at leastone low-frequency acoustic driver, and keep the at least two secondguiding holes closer to a user's ear than the at least two first guidingholes when the user wears the glasses.
 13. The glasses of claim 12,wherein the at least two first guiding holes and the at least two secondguiding holes are disposed on the supporting structure.
 14. The glassesof claim 12, wherein the supporting structure includes a first housing,the low-frequency acoustic driver is encapsulated by the first housing,and the first housing defines a front chamber and a rear chamber of thelow-frequency acoustic driver.
 15. The glasses of claim 14, wherein thefront chamber of the low-frequency acoustic driver is acousticallycoupled to one of the at least two first guiding holes, and the rearchamber is acoustically coupled to the other first guiding hole of theat least two first guiding holes.
 16. The glasses of claim 12, whereinthe supporting structure includes a second housing, the high-frequencyacoustic driver is encapsulated by the second housing, and the secondhousing defines a front chamber and a rear chamber of the high-frequencyacoustic driver.
 17. The glasses of claim 16, wherein the front chamberof the high-frequency acoustic driver is acoustically coupled to one ofthe at least two second guiding holes, and the rear chamber of thehigh-frequency acoustic driver is acoustically coupled to the othersecond guiding hole of the at least two second guiding holes.
 18. Theglasses of claim 1, wherein the sounds output from the at least twofirst guiding holes have opposite phases.
 19. An acoustic output device,comprising: at least one low-frequency acoustic driver configured tooutput sounds from at least two first guiding holes; at least onehigh-frequency acoustic driver configured to output sounds from at leasttwo second guiding holes, wherein a first distance is between the twofirst guiding holes, a second distance is between the two second guidingholes, the first distance exceeds the second distance, and the firstdistance is in a range of 20 millimeters-40 millimeters; and acontroller configured to direct the low-frequency acoustic driver tooutput the sounds in a first frequency range and direct thehigh-frequency acoustic driver to output the sounds in a secondfrequency range, the second frequency range including one or morefrequencies higher than one or more frequencies in the first frequencyrange.
 20. The acoustic output device of claim 19, wherein the seconddistance is in a range of 3 millimeters-7 millimeters.